Posted by
CowboyNeal
on from the heavenly-bodies dept.
loconet writes "The BBC is reporting that astronomers have discovered the first object ever that is in a companion orbit to the Earth. Asteroid 2002 AA29 is only about 100 metres wide and never comes closer than 3.6 million miles to our planet."
Re:meters, miles...
by
Anonymous Coward
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· Score: 4, Funny
NASA had the same problem... it only cost them $125 million.
Re:meters, miles...
by
bongholio
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· Score: 5, Funny
You think that's bad? As a student pilot, I've learned that the aviation industry has the biggest problem with unit consistency. Or maybe it's the weather industry... check out a _standard_ weather report...
KGTU 220115Z AUTO 15005KT 10SM OVC005 17/16 A3000 RMK AO1
here's what it all means:
kgtu = georgetown, tx airport
22nd of Oct, 0115Z, automated report
winds 150deg @ 5 KNOTS
visibility 10 STATUTE MILES
clouds overcast at 500 FEET
temperture 17deg CELCIUS, dewpoint 16deg CELCIUS
pressure 30.00 INCHES OF HG
remarks: A01=cannot distinguish liquid from frozen precip...
Anyways, as you just saw, the weather is reported using KNOTS, STATUTE MILES, FEET, CELCIUS, IN of HG. Damn! 3 painfully different systems of measurement.. and it seems the more i learn, the more stuff like this I see... I really wish us stubborn americans would just switch to SI...
Re:meters, miles...
by
bobdotorg
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· Score: 4, Funny
I really wish us stubborn americans would just switch to SI...
So what are the S.I. units for a good ol'/.'ing?
Hits?
Sysadmin pagings?
Attempted GB's of transfer?
I'm just imagining what the local newscast tease would sound like, "Scientists at Caltech are reporting a slashdotting of 7.4 on the POSA* scale, centered under poorslashdottedbastard.com. Film at 11."
POSA - Pissed Off SysAdmin
-- __
Someday, but not this morning, I'll finally learn to use the preview button.
Re:meters, miles...
by
Samrobb
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· Score: 2, Interesting
3 painfully different systems of measurement.
No... Four. A nautical mile is 6000 feet; a knot is one nautical mile/hour. A statute mile is ~ 5200 feet. Oh, wait - the wind direction is specified using a 360 degree circle, when it could also be expressed in radians, so really, that's five distinct measuring systems.
-- "Great men are not always wise: neither do the aged understand judgement." Job 32:9
Re:meters, miles...
by
jerde
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· Score: 2, Interesting
Of course, if one stands in the northern hemisphere, looking at the sun, the definition of "left" and "right" is one way.
Move to the southern hemisphere. You're now the other-side-up, and left and right are reversed.
This is now wandering off-topic even further, but: Have you every tried to define "left"? Pretend you're on the phone with aliens, who want to know what we define as "left".
Up, down are easy -- gravity based definitions are fine. But then try to describe clockwise, or right.
I come close when I have the alien move an electron in the "up" direction, and then try to define clockwise in terms of the direction of the magnetic field lines created.
But then you need a way to define the polarity of the magnetic field -- and I can't think of a naturally occuring magnetic dipole to compare it to.
Nasty brain twister, if you let yourself be kept up at night thinking about such things.:)
In Britain we use millibars for the pressure setting in our altimeters. Europe uses hectopascals. Fortunately 1 millibar = 1 hectopascal, so why change? We do have the same knots/miles/feet thing though. One plane crash was due to the crew having loaded so many pounds of fuel when they should have loaded so many kilograms instead...!
--
"Information wants to be paid"
Re:meters, miles...
by
mpe
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· Score: 3, Interesting
You think that's bad? As a student pilot, I've learned that the aviation industry has the biggest problem with unit consistency.
There is a series of Discovery channel involving building a light aircraft, one of the first points the presenter made was that the construction involved using strange mixtures of units. You also have fuel load on commercial aircraft being measured as a weight, thousands of pounds; whilst dispensed as a volume; either litres, US gallons or imperial gallons depending where the plane fills up. Messing up the cacluations leading to a flight crew having to test the gliding abilities of an airliner over Canada.
I really wish us stubborn americans would just switch to SI...
The US signed the "Treaty of the metre" a long time ago, the US Congress explicitally has the power to set weights and measures so it's really a political problem.
Re:meters, miles...
by
EmagGeek
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· Score: 5, Funny
Americans will NEVER switch to SI (much to my dismay).. Here's why:
Football players' union would demand a proportional increase in salary for the extra distance
Football stadiums are too short to extend to a 100m playing field and still have enough setback behind the end zones to comply with OSHA safety regulations
A quarter pounder sounds bigger than an eighth-kilogrammer, and 100g sounds tiny
Americans couldn't comprehend reciprocating fuel mileage (Liters/100km rather than mi/gal)
Tons of government software would have to be thrown out and/or rewritten for the switch (wait a minute.... they still use FORTRAN77 for stuff)
Having unified units throughout the world might be a threat to our national security (who the hell anywhere else knows what an URG is?)
Sears couldn't sell a 500 piece socket set, half of which is completely useless
What woman would ever admit to wearing a size 32 shoe or having a size 65 waistline? (Although they'd probably love having a size 86 chest or being 168 tall)
The Daytona 500 would become the Daytona 804.672, and that number is too big for NASCAR fans to comprehend (it was only recently that they could start having 600 mile races)
A Wendy's Triple w/ Everything has 810 caliories, which is bad enough. However it has 3,391,308 joules - try selling the biggie-size on that one!
Who wants to pay for gas by the liter? (or shall I say "litre")
Americans don't want to have to start mis-spelling (interject) everything, like "colour" and "litre" and "behaviour" etc
The mile markers on I-85 in Alabama couldn't be so cool anymore - now they go 1,1,2,3,2,4,3,5,6,4,7,8,5,9, etc....
and so on, so as you can see, conversion to SI in America wouldn't be worth the trouble...
Re:meters, miles...
by
vslashg
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· Score: 2, Funny
Sears couldn't sell a 500 piece socket set, half of which is completely useless
Why would that change?
Re:meters, miles...
by
gorilla
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· Score: 3, Interesting
One plane crash was due to the crew having loaded so many pounds of fuel when they should have loaded so many kilograms instead...!
This was the Gimli Glider, which didn't crash, but did run out of fuel and had to make a dead stick landing on the abandoned RCAFB Gimli. No-one was seriously hurt. The aircraft, registration C-GAUN, serial number 22520, is still in service after $1M worth of repairs. Here are some photos from earlier this year.
I really wish us stubborn americans would just switch to SI...
The Carter Administration tried this back in the 1970s. The plan was to gradually ease the U.S. into the metric system; the first step was to put up metric speed limit signs. Patriotic Americans responded warmly by shooting them down. So you could say that the metric system has not caught on very well here, unless you count the increasing popularity of the nine-millimeter bullet. (Paraphrasing Dave Barry.)
-- We're going down, in a spiral to the ground
Re:meters, miles...
by
zbuffered
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· Score: 3, Funny
"Scientists at Caltech are reporting a slashdotting of 7.4 on the POSA* scale, centered under poorslashdottedbastard.com. Film at 11."
"Scientists estimate the site recieved upwards of 4,000 hits in two minutes, or 3,451 hits metric."
Back in the mid 80's, NPR had a couple of fun articles about the non-celebration of the hundredth anniversary of the US going metric.
This needed a bit of explaining, of course. It turns out that the US, like most countries, actually has no legally-required system of measurements. There are laws (or more often, regulations) that specific items must be measured with specific units. But there is no overall requirement that all measurements be in the same "system".
However, the US government has always had an official standards body. It has had various names and acronyms, such as NBS (National Bureau of Standards) or NIST (National Institute of Standards and Technology). It basically manages the regulations that say "If you use unit U, you must use the official definition of U, which is...."
So how did the US "go metric" in the 1880's? Well, what the national standards bureau did then was to revise the official definition of all terms of measurement. They've done this many times. At that time, they decided that the best system in use by scientists and engineers was the "metric" system centered in Paris. There were already copies of the metric units in the US, and they were used for calibration. What was done was to make this official, and publish definitions of all the common units as multiples of the metric units.
These definitions have mostly continued. Thus, the legal definition of an inch is 0.0254 meters. This is not an approximation. It is exact, because it's the official definition of "inch".
It occurred to me while listening to the NPR articles that what the US has is what we in the computer field would call an "extended metric system". We have all the metric terms, but we also have a whole lot more. This obviously makes the American system more versatile, right?
So it's really an example of "embrace and extend."
-- Those who do study history are doomed to stand helplessly by while everyone else repeats it.
I was recently in Engalnd, feeling like a teenager again, not sure which side to drive on, which way to look at an intersection, etc. But, when I filled up at the gas station, it was like they were catering to Americans (or maybe to Brits, who might still be familiar with gallons). Next to every pump, they had a handy "liters to gallons" conversion chart, so you could tell how many gallons you were filling, AND how much the gas was per gallon. I felt better pumping gas in England than I did in New Jersey (where all the pumps are full service, and you might be SOL if you work late shift and need gas at 3 in the morning).
In the U.S. we would integrate the conversions in the gas pumps, with dual sets of displays, or a button to toggle displays. Of course, we wouldn't be able to switch until most of the population had taken a thermodynamics course (or at least a chemistry/physics lab), and learned first-hand how much easier the metric system can be. And THAT won't happen until we get most Americans through a biology class without a big contreversy over evolution...
Re:meters, miles...
by
tetranz
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· Score: 3, Interesting
I'm curious. How much has the UK really changed? Are road distances Km or miles? And road speeds?
Twenty something years after New Zealand changed to metric I find it interesting and a little disappointing sometimes to observe the results.
Degrees F quickly disappeared because (I assume) of TV weather forecasts. MPH has gone because of car speedos but I think you would get blank looks if you asked a mechanic or tyre installer about pressure in Kpa.
Pounds and ounces seem to be long forgotten except for babies' weights.
Commercial floor space still seems to be advertised in sq ft, land area often in acres although I'm sure the official documentation is metric.
Off the cuff comments on TV by police etc at the scene of some event will often make it clear that feet and yards are still more comfortable than meters.
New born babies' weights are more often than not quoted in the newspapers in pounds.
Some adults still quote weight in stones (14 pounds?) although I doubt that you can even buy scales with stones now.
Re:meters, miles...
by
squiggleslash
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· Score: 3, Informative
But, when I filled up at the gas station, it was like they were catering to Americans (or maybe to Brits, who might still be familiar with gallons). Next to every pump, they had a handy "liters to gallons" conversion chart, so you could tell how many gallons you were filling, AND how much the gas was per gallon.
Ironically it wouldn't have helped. British gallons are about 20% larger than American gallons. I kid ye not, this was one of the first things I learned on moving to the US.
Britain switched over to litres in the last decade, so most drivers were brought up to think in terms of gallons. I bet quite a few are doing the conversion in their head every time they see the prices at each petrol station...
-- You are not alone. This is not normal. None of this is normal.
This was the Gimli Glider , which didn't crash, but did run out of fuel and had to make a dead stick landing on the abandoned RCAFB Gimli.
It was decomissioned, not abandoned. In this case, Gimli had 32L and 32R. 32R was still being used as a civilian runway, but 32L (where the Gimli Glider landed) had been converted to -- and was being used as a racing facility.
("being used", here referring to the fact that it was "Family race day" for the local racing club... the runway was stock full of people... Talk about a photo op!).
The reason why the plane landed on top of an actively used drag strip was that by the time they got close enough to realize what was going on there, they didn't have the spare airspeed/ altitude/ attention span to divert a few hundred feet to the right. On the bright side, though... having landed in the middle of an amateur race fest, there were literally hundreds of hand-held fire extinguishers available to help fight the (relatively small) fire that broke out as the plane skidded to a halt (hydraulic fluid?).
Read the link . It's an entirely worth your time. (at least, it was for me!)
-- Sometimes boldness is in fashion. Sometimes only the brave will be bold.
Um, I live in the US and I've never heard of an "URG". Do you mean erg, by chance?
No. URG. An URG is the sound you get from a pilot when fuel requirements are calculated in kilogram but loaded in pounds resulting in a flame-out halfway through the flight. (actually, the quote was "oh, F___", but I'm going to take some artistic license here)
It's a measurement of surprise*fear.
-- Sometimes boldness is in fashion. Sometimes only the brave will be bold.
Degrees F quickly disappeared because (I assume) of TV weather forecasts.
I think it's because C makes more sense for most people. 0C is where ice forms, and 100C is where water boils.
0F is where salt becomes about as useful as as sand, but that doesn't really matter to most people. 100F as is 212F (but in a different way).
MPH has gone because of car speedos but I think you would get blank looks if you asked a mechanic or tyre installer about pressure in Kpa.
Almost the same thing here in Canada. Air pumps are almost randomly in KPA and/or PSI with conversion tables nearby. I still think in PSI.
Having gone through school during the 'big conversion', I can pretty much think in either metric or English. Younger Canadians are mostly locked down to metric, these days.
Acres for land makes sense. 99% of all the land doled out in the former colonies was done under the Imperial system. If you've got an acre of land, it's pretty silly to describe it as 2.47 hectares.
For most human purposes, metres and yards are pretty much the same. but an 8 foot 2x4 still needs to be replaced with an 8 foot 2x4 -- no matter how you measure it. New houses, on the other hand, are all built in metric (makes it fun for the lumber stores).
When going through a conversion, you pretty much learn some quick conversion estimates:
1foot =~ 30cm;
1Metre=~~ 1yard; and miles->KM @ 1->1.6 is reasonably estimated at 2->3.
Degrees C =~ 2DegreesF for small increments, but the 5/9 ratio is exact (or 10/18) so it's not that big a computational expense.
-- Sometimes boldness is in fashion. Sometimes only the brave will be bold.
Please, say you pulled that out of something/besides/ those tacky S&M novels thinly disguised as fantasy/science fiction.
Of course, maybe/this/ asteroid has the world where the men are all required to do the bidding of the women... with far fewer stupid sci-fi trappings. Then, the news might actually interest me.
i was actually referencingthe marvel comics counter earth, the high evolutionary and the knights of wundagore and whatnot, i don't remember much of it, i'm not that into comic books
-- "Sic Semper Tyrannosaurus Rex."
Earth's second moon
by
EggplantMan
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· Score: 5, Interesting
Not only is it co-orbital but it periodically gets trapped in earth's gravitational field to become a second moon:
General Simon Worden of the United States Space Command described it as a "near Earth object that is close to being trapped by the Earth as a second natural satellite".
...
In 550AD, and again in 2600AD and 3880AD, for a while it will become a true satellite of our planet, in effect Earth's second moon, although technically it will remain under the gravitational control of the Sun.
Not only is it co-orbital but it periodically gets trapped in earth's gravitational field to become a second moon:
Okay, I am no astronomer, nor English major, BUT I am confused all the same.
How can it be "periodically trapped"? Is it like the object orbits Earth a few times and then skips back off through the cosmos?
What about that business of every bit of matter in the universe exerting gravitational force on every other bit all the time? Is this object magically shielded from earth sometimes, except for when it is "periodically captured" by Earth?
Am I confusing periodic capture astronomy in the same way I confuse regular physics with quantum physics?
No, I am not trying to be a wise ass, these terms do not make sense the way they were preseted to me.
Re:Earth's second moon
by
rebelcool
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· Score: 3, Interesting
the orbit is as such that after orbiting earth for awhile, it builds the momentum to escape earth's orbit and fling itself back out and around the sun.
Interplanetary probes use this method all the time for escaping earth's gravity. After launch, they orbit the earth for awhile building up momentum (this is known as a 'gravity assist') then fling themselves out.
This is actually a much more common cosmic event than actually capturing something in permanent orbit. Doing that requires careful placement in the case of artificial satellites or just random chance in the case of natural ones.
The moonlet is orbiting the Sun in an orbit that is either a little more distant from the Sun, or a bit closer to the Sun than the Earth's orbit. The switcheroo goes like this...
Your explanation reminds me of square-dancing moves. Perhaps square dancers will grok it faster than mere mortals. Perhaps that is why the big space centers are in Texas:-)
"Dosey doe and around we go. Now trade partners and then let go....."
I tried square-dancing once. But I screwed it up and somehow ended up dancing with a guy. That is when I gave it up. I would make a lousy near-planet asteroid I guess. (Hmmmm. Maybe the other guy was gay and rigged it somehow, and thus not really my fault after all.)
600 years?
by
cybermace5
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· Score: 5, Interesting
They claim it will be temporarily in earth orbit by 2600 AD. And then they go on to speculate on how important that would be to space exploration, possibly becoming the second object visited by astronauts.
If, in 600 years, we haven't sent astronauts to visit other planets, I have preemptively lost faith in the human race.
Come on, in 600 years we should have a pretty decent Mars colony going.
Detailed observations of its trajectory through space show that 2002 AA29 will reach its minimum close approach to the Earth - 12 times the distance between Earth and the Moon - at 1900 GMT on 8 January 2003.
It will be closest to Earth in 2003, and will be nearby for awhile after. As it is much, much closer than Mars, it very well may become the next body visited.
Well shit, in 600 years I'll take my own goddamm air car and go visit it myself. Needless to say I'm still impatiently awaiting my cure for old age and (naturally) my flying cars but these are pesky details...
I *pray* (and I am not a religious man, so it gets confusing... who shall I pray to tonight?) that we will visit something else before 2600. Preferably in my lifetime, but I guess that's not important in the long-term sense.
If we spent a little money on it (a little compared to, say, what we spend on defense) we could go to mars NOW. Or at least, very soon. All of this bullshit warmongering that we waste our time and money on is really keeping us from greatness. Of course if we didn't spend it on war we'd probably spend it on something dumb like theme parks or big oil.
We should DEFINITELY have gone to Mars and be actively moving colonists there long before 2600, barring some kind of serious event. It's just going to become too lucrative not to for some reason or another.
-- "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Well, it may not actually be the best time to launch at that time. The article didn't say how far away it ever gets (which could tell us how fast it moved). But my argument is that if it gets really far away, that means it's traveling very fast when it passes earth, and so you may want to wait until it has a lower relative velocity near the farthest point. Or it isn't traveling that fast when it passes earth, and you can afford to wait.:)
No, but I suspect it would be very possible, in say, the next 20 or so years that it will be in our neighborhood. It takes 90+ years to complete a cycle; it's not like it's going to zip away all of a sudden.
---snip It has two "near" points to the earth (ahead and behind). Thus wouldn't it take 45+ years (rather than 20) until it gets close enough again? 20 years would put it at the farthest possible distance. ---snip
It would if the round trip took 95 years, but but 95 years only gets you a one way visit. From the article:
Thereafter it will travel ahead of the Earth moving faster than our planet does, until after 95 years it will catch up with the other side of the Earth and then reverse its motion.
So a one way trip takes 95 years...an out and all the way back trip would take 190 years. So at 20 years it would be a quarter of the way along, and at 47.5 years it would have reached it's furthest point.
I'm betting within 10 years there will be an accord preventing any country from stepping on any other celestial body because it would affect its environment.
I think it has to be a bit larger. A space elevator has an awful lot of mass to it. A 100 meter asteroid wouldn't do that much good as a counterweight. Let's see, 50m radius -> 525,000 cubic meters internal volume. Assume it's a fairly heavy rock, say, 5 g/cm^3. That equates to 5 metric tons per cubic meter, or slightly over 2.6 million tons for the whole thing. I think that to be able to put the counterweight near GEO, it has to be on the order of billions of tons. Plenty of those out there, though.
It most certainly does! The center of mass of the elevator has to be at geosynchronous orbit. You can accomplish this either by simply building it twice as long as it needs to be or by sticking some large mass on the space-end of the thing.
and it isn't that heavy either, less than a thousand tons, depending on the structure.
Everything I've read says that 5000-10000 tons would be the absolute minimum. That's assuming a carbon nanotube cable with a earth-end surface area measured in square millimeters. It goes up very quickly from there. And the closer the countermass is to GEO, the bigger it's gotta be.
Oh, and nobody modded me up. Cowboy Neal loves me so much (even more than hot grits!) and so everything I say here on/. automagically ends up at 2.
-- Dyolf Knip
31337 413NZ!!!
by
Anonymous Coward
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· Score: 3, Funny
But despite detailed searches no one has yet found any Trojan objects near the Earth.
Next come the inter-stellar port scans.
Re:Not quite a planet, eh?
by
jamie
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· Score: 5, Interesting
"In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit."
No, any object in the same orbital path travels the same velocity.
Think about it this way. If I have a heavy object and a light object orbiting at Earth's distance from the sun, by your hypothesis one will travel faster than the other. So if I duct-tape them together they should travel at a speed somewhere in-between the fast one and the slow one. But the taped-together object masses the sum of both smaller objects so it should travel faster. It can't travel both faster than and slower than its larger half, so the hypothesis can't be right.
See the orbital motion for yourself
by
StupendousMan
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· Score: 5, Informative
JPL has a very nice tool for looking at the orbits of asteroids. Go to
Keep in mind that the orbital solution is based
on only a short arc: only 28 days, about one twelfth of a complete revolution. Our estimates of the orbital parameters -- and behavior --
could change quite a bit over the next few months.
-- Michael Richmond "This is the heart that broke my finger." mwrsps@rit.edu http://stupendous.rit.edu
Re:See the orbital motion for yourself
by
rjkimble
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· Score: 2
It's common in orbital studies to use a moving reference frame that fixes two objects -- in this case, the earth and the sun -- and let everything else move with respect to them. When you do switch to such a reference frame, the asteroid's orbit looks a bit like a horseshoe with the sun at the center. This kind of reference frame is especially useful for viewing the magic of the Lagrange points.
--
Guns don't kill people -- people kill people. But the guns seem to help a bit. (apologies to Eddie Izzard)
Re:See the orbital motion for yourself
by
geoswan
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· Score: 2
WTF are they talking about when they say "horseshoe" orbit. Doesn't look the least bit horseshoe like to me...
Go back to the JPL thing, and make it have its point of view focus on the Earth. Now look at the line that represents 2002 AA29's orbit? But 2002 AA29's orbital path ranges over a kind of ribbon, because the Earth speeds it up and slows it down, as explained here.
So think of a picture centered on the Earth. 2002 AA29 approaches Earth, but it doesn't come too close. So if you map its location, relative to the Earth, the two horns of the horseshoe shape represent its closest approach when leading and when trailing the Earth. The rest of the time it is somewhere in that ribbon.
Its period around the Sun, its year, varies in length, when the Earth has slowed it down, it is closer to the Sun. That bounds the inner part of the horseshoe shape. When the Earth has sped it up, that bounds the outer part of the horseshoe shape.
Better get the calculations right!
by
Randar+the+Lava+Liza
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· Score: 3, Insightful
They better not have any of those metric conversion errors if they try this operation:
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
cough Mars Climate Orbiter cough.
-- Life shrinks or expands in proportion to one's courage.
- Anais Nin
Earth: "MOMMMMMMM! AA29 won't leave me alone! Please tell him to play on the other side of the solar system?!?"
Tal
--
"Study your math, kids. Key to the universe." -The Archangel Gabriel
Re:Not quite a planet, eh?
by
ocie
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· Score: 5, Informative
Interesting physics, but Kepler's third law says:
The squares of the periods of the planets are proportional to the cubes of their semimajor axes (http://home.cvc.org/science/kepler.htm).
So the mass of a planet has nothing to do with its orbital period (well, assuming it is small enough that it doesn't make the sun orbit it). So anything placed at Earth's distance from the sun and moving at the same speed would orbit the sun in the same path the Earth does regaurdless of its mass.
The Earth of course revolves around the sun completing one revolution every year, but the Moon also revolves around the Earth in its own orbit.
Whether this new planet is actually a satellite of Earth is still to be determined. Also, a similar orbit does not mean that the climate is also known to be similar a priori.
The Earth's ecliptic orbit in summation with the Moon's orbit around the Earth means that the Moon must intersect the ecliptic; in fact, it will have to do so at two distinct points.
Has anyone found these nodal points for "Earth's Little Brother" yet? That's the true test of whether or not we will truly be affected by such circumstances.
Re:Orbits, nodes, & more
by
saforrest
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· Score: 2, Funny
Also, a similar orbit does not mean that the climate is also known to be similar a priori.
Climate?? Did you miss reading that this thing is like 100 metres wide? What kind of climate are you expecting?
At the most, we could expect an asteroid of that size to support a little boy, maybe some sheep, and a flower.:)
The Earth of course revolves around the sun completing one revolution every year,
The Earth takes one year to orbit the sun. It also rotates on its axis at a rate which has nothing at all to do to the orbital period. Currently the Earth rotates just over 366 times per orbit. What we measure as a "day" is slightly more than one revolution of the Earth, because the Earth has moved a considerable distance in the time taken to revolve around its axis once.
but the Moon also revolves around the Earth in its own orbit.
The Moon rotates on its axis exactly once per orbit. Hence it keeps the same face towards Earth all the time.
Re:Orbits, nodes, & more
by
saforrest
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· Score: 2
Up until now (13:20CEST), there still isn't any moderator that got it... Don't you guys read classics? Antoine de Saint Exupery must be turning in his grave (well, if he had one...)
Sigh... believe it or not, it's good to know there is at least one person who got the reference, though.:)
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
I can see it now: "Thanks to a sucessful nudgeing, scientists have been able to determine that Asteroid AA29 is pretty much a big rock. In other news, bizarre tides continue to cause panic and destruction around the world tonight..."
This is a new and interesting experience. I'm genuinely not sure whether you're making a reference to Jonathan Swift or computer architecture. The mind reels.
Re:Not quite a planet, eh?
by
targo
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· Score: 5, Informative
roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit.
Wtf? Orbital velocity is a constant that depends only on the mass of the parent body, as long as the orbiting body is significantly lighter. After all, geosynchronous satellites are all at approximately same height, although they have the same speed (to maintain synch), but different mass.
The formula for calculating orbits is: T=2*pi*(a+h)/v where T = period, a = radius of the parent body, h = orbit height, and v = satellite velocity, which can be calculated from: v = sqrt(g/(a+h)), where g is gravitational acceleration of the parent body. You don't see the mass of the satellite anywhere here.
In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit.
Ye gods! This is false.
Hint: why does a low earth orbit -- like the Space Shuttle's -- always take the same time? Orbital period depends only on the mass of the earth and the radius of the orbit, not of the satellite.
So why won't 2002 AA29 ever hit the earth?
Do a google search on the Jovian Trojans. Or look up Lagrange Points. Or just consider the complexity of a three body system.
-- Unlimited growth == Cancer.
Horseshoe orbit?
by
jovlinger
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· Score: 3, Insightful
Can sny rocket scientists out there explain how two bodies in the same orbit can have different velocities, AND how the relative velocities can change over time?
They claim that for 90 odd years, the asteroid will accellerate ahead of us, to catch up with earth from behind, at which point it will fall back and we'll cath up with it. And then it repeats.
weird! I can't figure out how this is comes about, and the article didn't think it worth mentioning.
Re:Horseshoe orbit?
by
Link310
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· Score: 5, Informative
As I understand it, it is not in *exactly* the same orbit, but sometimes inside it and sonetimes outside it.
Say at some moment it is *just* outside the Earth's orbit. It is therefore travelling just slower than the earth, and falling very slowly behind - so slowly that it takes 95 years for the earth to lap it. However, when the earth does lap it, as it comes up behind, the earth attracts the asteroid which, for a period, circles the earth. After whizzing aroind the earth for a while, it gets flung out of earth orbit (conservation of energy says that it has too much energy to remain in earth orbit forever). However, it gets flung out just *inside* the earths orbit - a little closer to the sun and travelling a bit faster than the earth. So this time it creeps ahead of the earth, taking another 95 years to catch up. When it creeps up on the inside track, it gets another whirl around and comes out again back where we started, on the slow track, falling behind the earth again.
From a geocentric point of view, it appears from the other side of the sun, whirls round the erarth a few times, then disappears back where it came from, reappearing some years later from the opposite direction, having another whirl, and dissappearing back where it came from again. Hence the "horseshoe shaped" orbit - funny looking horseshoe if you ask me.
-- Consciousness is an illusion caused by an excess of self consciousness.
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
Uh, wouldn't that screw up the tidal system?
Yeah, but so what? Our species has a track record of fucking up the environment for the sake of profit. At least now we'd be fucking up the environment for the sake of science.
Doesn't reflect very well on humanity,does it...
by
Mac+Degger
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· Score: 2, Insightful
I mean, come on...if we're as advanced as we seem to think we are, we should have been able to land something on it on jan 8, 2003.
Yeah, I know, that kind of thing is complex, but I feel we should have that spurious launch capability...god knows it would save us if we ever met something like what hit Jupiter a couple of years back.
-- --
Waht? Tehr's a preveiw buottn?
20K libertareans...
by
Anonymous Coward
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· Score: 5, Funny
... now have the perfect candidate for their "free" state.
Re:Not quite a planet, eh?
by
GreenPhreak
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· Score: 5, Informative
The reason this discovery is useful and more than 'whoop-de-doo' is because of what was mentioned in the end of the article: it is an extra-terrestrial body that is very close to the Earth. It would not be outside our reach to visit this object with current technology and learn more about the composition of asteroids and other minor planets in the solar system.
It is also intriguing since no 'trojans' have been discovered for the Earth and this could signal that we do in fact have some. Trojans are asteroids that occupy the 4th and 5th Lagrangian points about a larger body (Jupiter has the most, due to its large mass). Because of the physics involved in a 2 body system where any additional bodies have negligible mass compared to the original 2, there are a few 'stable' points where the gravitational forces cancel out...these are known as Lagrangian points. L4 and L5 are co-orbital to the less-massive object (Jupiter, Earth, whatever).
Although this object is not a trojan, since it has a horseshoe orbit and temporarily gets caught up in Earth's orbit, it suggests that there are bodies out there that could be trojans. Perhaps as our detection abilities progress, we will discover some Earth-trojans.
-- I drink to prepare for a fight; tonight I'm very prepared.
-Soda Popinksi
Forgetting our history?
by
vikstar
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· Score: 2, Funny
But despite detailed searches no one has yet found any Trojan objects near the Earth.
"The Greeks built an immense wooden horse and Odysseus, Menelaus, and other warriors hid inside it. After leaving the horse at the gates of Troy, the Greek army sailed away. The Trojans thought the Greeks had given up and had left the horse as a gift."
-- The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.
Re:Forgetting our history?
by
David+Walker
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· Score: 2, Funny
yeah, man, what they're saying is they haven't found any asteroids with disgruntled greek warriors inside them near earth
Re:Forgetting our history?
by
The+Cydonian
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· Score: 2, Informative
A Trojan asteroid is "any planetoidal body at the triangular Lagrangian point of any two bodies" named thus because the Trojan asteroids of the Sun - Jupiter system are named according to the Illiad.(Wikipedia). There's an interesting webpage on the Trojan asteroids in the Sun - Earth system here
I wonder how hard it would be to pull that asteroid to earth orbit for mining or as an anchor to a space elevator, a la the [almost] original concept by Arthur C. Clarke (later designs use a man made anchor).
If we can mine useful materials, we could build some cool, big ass stuff probably cheaper than we would carry all that weight from the surface.
--
There are two kinds of people in the world: Those with good memory.
Re:Not quite a planet, eh?
by
geoswan
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· Score: 4, Informative
Of course, the part I don't get, *why* can't it hit the Earth? In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit...
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects. So, how much do you think the sum of the masses of the sun and the Earth differs from the sum of the masses of the sun and 2002 AA29?
There are lots of explanations of horseshoe orbits on the web. Basically, if two objects share the same, or very similar, orbits, they are attracted to one another. That gravitational attraction drains kinetic energy from the leading object, and slightly adds kinetic energy to the trailing object.
The leading object, having lost energy, moves closer to the primary. Its year gets slightly shorter, and its actual velocity relative to the primary speeds up. Similarly, the trailing object moves farther away, and its year grows slightly longer.
So the leading objects closer orbit has it revolve around the Primary more quickly, and it will slowly move away from the trailing object. Eventually the leading object is exactly opposite from the trailing object. According to the BBC article, this takes 95 years.
Once the object that was leading is more than 180 degrees ahead in it orbit from the object that was trailing, their mutual attraction starts to add energy to its orbit, and raise it to a higher orbit. Similarly, the mutual attraction drains energy from the other object.
What we have just seen is the two objects trade places. The object that was the trailing object is now the trailing object.
It seems paradoxical that mutual attraction should tear the two object apart. Until you remember that the Sun's influence on the object's trajectories is much more important than their attraction to one another.
At least that is my understanding of the BBC's article.
How does this mechanism allow 2002 AA29 to be briefly captured by the Earth? I'd welcome an explanation of this.
If we are able to collect enough of these "friendly" asteroids, or "trojans" as the article calls them, we can think of establishing colonies on these. Along with space elevators, there will be micro-colonies on each of these asteroids, between which people can travel, just like between different continents. The only issue is when the asteroids decide to take a different orbit!
-- "Do something man. Right now."
Re:Friendly asteroids - colonisation!
by
mpe
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· Score: 2
If we are able to collect enough of these "friendly" asteroids, or "trojans" as the article calls them, we can think of establishing colonies on these.
"trojans" usually refers to asteroids captured in L4 and L5 positions. Usually the Jupiter/Sol Lagrange points. These are 60 degrees away in the orbit. Earth/Sol L4 and L5 are about an AU away from Earth. The Luna/Earth Lagrange points are rather more useful.
Along with space elevators [slashdot.org], there will be micro-colonies on each of these asteroids, between which people can travel, just like between different continents. The only issue is when the asteroids decide to take a different orbit!
Not really a problem for a space elevator. The only major trick is making sure that the centre of mass is in equatorial geosynchronous orbit at all times. You start construction in the orbit you want and build a structure going both "up" and "down".
Knew this was coming
by
Babylon+Rocker
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· Score: 2, Funny
Re:Brother? Yes, it is a minor planet
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saskboy
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· Score: 3, Insightful
Any body of rock that is orbiting the Sun and not another planet, is a minor planet if it is not a major planet like Mercury, or Jupiter. Asteroids are also known as minor planets.
Re:Second Moon
by
gurensan
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· Score: 2, Informative
No. It's too small. It's like passing a hand-size natural magnet 50 feet away from iron filings.
-- You are all fartheads.
Re:Doesn't reflect very well on humanity,does it..
by
GreenPhreak
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· Score: 2
Yeah, I know, that kind of thing is complex, but I feel we should have that spurious launch capability...god knows it would save us if we ever met something like what hit Jupiter a couple of years back.
I don't think having a spurious (false, unauthentic) launch ability would permit us to escape fiery death at the hands of a rogue shoemaker-levy-like object. Perhaps you mean extemporaneous. All jokes aside, it would be great to have a near-impromptu method for launching, but unfortunately missions are really expensive and require a great deal of planning. With the derth of funds going towards NASA these days, it should be expected that we won't have improvised launches anytime soon.
-- I drink to prepare for a fight; tonight I'm very prepared.
-Soda Popinksi
No, it would be idiotic. The moon stores a huge amount of angular momentum. That's energy, folks. Let's see... we could waste a whole lot of energy trying to stop it, or we could leave it as it is so that years from now we may harness it usefully.
Anyone read _Signal to Noise_, incidentally? Great book.
The phases that the moon goes through (waxing and waning and whatnot) has nothing to do with the rotation of the moon
Umm I'm pretty sure that he made the original comment in jest.. I doubt anyone who posts to slashdot is ignorant enough to think that the lunar cycles have anything to do with lunar rotation.
Re:BBC, News for Nerds & stuff that REALLY mat
by
Doomrat
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· Score: 2, Informative
Which is exactly why we'd want to be forgetting Fox news.
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects.
Err... the force is proportional to the product of the two masses: F = -G M m / r^2;... not the sum.
--
This post is strictly my own opinion and not necessarily that of my employer.
Actually this proves counter earth aint there
by
goombah99
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· Score: 2
If counter earth were there it would bash into it. And of course the counter-brother planet would bash into us at the same time. So no bizaro world. Bummer.
-- Some drink at the fountain of knowledge. Others just gargle.
Re:Not quite a planet, eh?
by
GreenPhreak
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· Score: 2
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects.
Maybe if you did have the equation for the gravitational attraction between two bodies nearby you'd realize that it is a function of the PRODUCT of the masses of the two objects.:>
F = (G x m1 x m2)/(r^2)
-- I drink to prepare for a fight; tonight I'm very prepared.
-Soda Popinksi
To make maters worse...
by
GMontag
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· Score: 3, Funny
I military aviation, we have all of that you mention plus, on the topographical maps, the horozontal distance is in kilometers (metric) and the vertical distance/elevation is in feet! The good thing is the altimiter is in feet too, but still...
I military aviation, we have all of that you mention plus, on the topographical maps, the horozontal distance is in kilometers (metric) and the vertical distance/elevation is in feet! The good thing is the altimiter is in feet too, but still..
But your speed is measured in knots, so you need convert back and forth between kilometers and nautical miles.
Re:Not quite a planet, eh?
by
MCZapf
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· Score: 3, Interesting
I never quite understood the concept that an object in orbit is "falling around the sun (or earth)" until I read a physics book that got me to visualize this:
Imagine you have a cannon. You fire a cannonball out of it, and it follows a parabolic path until it hits the ground (Boom). Now, you get a more powerful cannon, and fire a cannonball even farther. In fact it's so powerful that the cannonball is traveling so fast horizontally that the ground is receding from it, due to the curvature of the Earth, faster than gravity is pulling it down to the Earth!
Tada! So the cannonball just keeps moving, around the Earth. It's in orbit.
I hope that explanation helps at least one person who was like me.
Zookeeper Hypothesis
by
gnarly
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· Score: 5, Interesting
The Fermi Paradox asks: If intelligent life is common, given the billions of years since the formation of our galaxy, why have E.T.'s not yet reached (and perhaps colonized) Earth?
One proposed resolution is the Zookeeper Hypothesis, ie, they could have contacted us but are just waiting and watching for us to evolve, a la 2001.
If so, then wouldn't they want to put a probe near the Earth, which swoops down every few centuries or so for a close look, to see if any thing interesting has happened?
One proposed resolution [space.com] is the Zookeeper Hypothesis, ie, they could have contacted us but are just waiting and watching for us to evolve, a la 2001.
The idea of not bothering less advanced cultures occurs quite a bit in science fiction. Possibly the best known would be the Star Trek prime directive.
If so, then wouldn't they want to put a probe near the Earth, which swoops down every few centuries or so for a close look, to see if any thing interesting has happened?
If you wanted to build something to watch Earth then Luna makes a far better place. It's rotation locked with Earth and big enough to hide even a large facility.
Well, maybe intelligent life is a property of our universal system that only emerges after a given period of time. Maybe all life in the universe emerged about the same time, and developed at the same speed as us. Or as someone else said, maybe intelligent life in the rest of the universe is very, very different from us. Heck, maybe we don't even qualify as intelligent life to the rest of the universe. What would superintelligent interstellar plasma clouds want with us anyway?
The answer to the question "why has no intelligent life contacted us?" is pretty simple: intelligent, starfaring species enough like us to communicate are not common enough that we have met any. Duh!
Why assume that our type of life is common when the actual evidence says otherwise? Because our theories say it should be common? I thought we tossed out theories that don't match the evidence.
-- -
None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Here is Paul Wiegert's information on Cruithne, which has much of the same characteristic as this current space body, but his explanation actually makes sense for what appears to be a horseshoe orbit, when in reality it's only a horseshoe orbit from Earth's perspective, and is relatively sane looking when viewed off of the solar system plane.
--
IBM had PL/1, with syntax worse than JOSS, And everywhere the language went, it was a total loss...
Re:Not quite a planet, eh?
by
jericho4.0
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· Score: 2
Guys, Galieo had a look at this one, once. Thinks about it. Objects of different masses accelerate at the same rate in a uniform gravitational field. The duct-tape anology is perfectly correct also.
-- "A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
Not a paradox.
by
Chris+Burke
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· Score: 3, Insightful
Neither your sig nor this sentence contains a paradox.
Re:Couple of comments
by
plutonium+binky
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· Score: 2, Funny
maybe its a stalker...like one in grade one or something...
oooh someone has a crush on earth.:|
all the good comments were already taken.
Re:Even better explanation:
by
Chris+Burke
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· Score: 2
That's only an explanation, not an argument. You're just -illustrating- that two objects would move at the same velocity, not -proving- it. So the other analogies were better.:)
'quite some time' is quite a bit longer than 12 months.
--
-
Little brother planet? Dammit
by
Nathdot
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· Score: 3, Funny
So just like that it shows up into our lives and we're meant to be all happy about it.
And I suppose we're expected to step in if Mercury or Venus start trying to take it's lunch money. And you know they're just gonna have a bigger brother as well. Don't we have enough problems with global warming and the like, without actively looking for trouble?
EXT. SPACE
2002 AA29:
You better not pick on me or gonna get my brother earth and he'll kick your ass!
MERCURY:
Oh yeah, I'd like to see him try.
EXT. SPACE - LATER
EARTH:
(sigh, to Mercury)
I heard you were giving my little brother shit.
(menacing)
What're you going to do about it now?
MERCURY:
Have you met my brother Jupiter?
From nowhere the gargantuan JUPITER appears.
EARTH:
Oh shit! Ay-Ay run!!!
When will we, the citizens of earth, ever learn that violence never solves anything.
the miniature X10 cameras in the miniature SUVs...
Mr. Bass's Planetoid!
by
tekrat
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· Score: 3, Interesting
Gosh doesn't anyone read the SF of children's writer Eleanor Cameron?
She wrote "The Wonderful Flight to the Mushroom Planet", but in "Mr. Bass's Planetoid", she created a tiny asteroid that allowed the two young protagonists to view the Earth while having landed their spaceship on this asteroid.
Next thing you know, the BBC will report that we've discovered Lepton! Watch out Mushroom People, we're coming!
-- If telephones are outlawed, then only outlaws will have telephones.
What they're saying is they're scouring the space beyond the mesosphere for used condoms. Those things can wreak havoc on a satellite, let me tell you.
The Fermi Paradox [ufoskeptic.org] asks: If intelligent life is common, given the billions of years since the formation of our galaxy, why have E.T.'s not yet reached (and perhaps colonized) Earth?
Because they're intelligent enough to stay away from this dump.
Re:libertarians should be gassed
by
Myco
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· Score: 2
Hey, that's not funny. I heard that actually happened to some people a while back.
I noticed a few people wondering how this would affect our planetary tides, orbit, etc. This would NOT affect the earth at all. Hell, it wouldn't even make that big of a crater if it hit us (why do I think I'm going to get flamed for that?)
The thing is 100 meters wide. Imagine a 100 meter (300 foot) wide ball. If we just grabbed it and brought it to earth's surface (gently), it still wouldn't affect our tides at all. It's small enough to fit in a stadium. It's the size of a big hill. The point is that it wouldn't affect us at all.
Also, the reason it wasn't seen that long ago was that it was too far away and too small to see with the naked eye. (we could barely see it with a scope).
-- The best way to predict the future is to invent it.
I noticed a few people wondering how this would affect our planetary tides, orbit, etc. This would NOT affect the earth at all.
An object this size would have less effect on an ocean than flying an airliner over the same ocean. Gravity follows an inverse square law. I'm not even sure an asteroid made of nutronium that size would have sufficent mass to cause much in the way of tidal effects.
Hell, it wouldn't even make that big of a crater if it hit us (why do I think I'm going to get flamed for that?
Actually the worst thing an asteroid can do is hit the ocean, since a tsunami can propergate over an entire ocean basin. This isn't even than big compared with typical sea depth.
a real answer to Fermi
by
commodoresloat
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· Score: 4, Interesting
Or rather, a question; who's to say that other intelligent life in the universe is anything like our species? The idea that they can and should colonize us, study us, or even visit us seems like the height of anthropocentric hubris. They might not be "flesh-and-blood." They might have a completely different relation to matter and energy as we understand it. They might live in water. They might have no interest in enslaving us or looting our precious natural resources.
Re:a real answer to Fermi
by
evilviper
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· Score: 2
They might live in water.
Hmm... Perhaps they are relatively small, bottle-nosed creatures? Let's call them dolphins. They mastered space travel, but had never before come across adversaries such as they found on earth. Their sonic waves of destruction had no apparent effect on us. For some reason we seemed actually drawn to it.
Their space craft resembled wooly elephants, which early man promptly killed ate.
Some time later, The president made a sacred pact with them, that they would get to live in peace on their land. That worked just fine until we found gold on their land, and promptly pushed them into the ocean. Then, to make things worse, we began dumping large ammounts of sewage on them, which they didn't like one bit. Occasionaly a few rebels will climb up onto the beach to try and take back their land. However, those evil tree-huggers hose them down and push them back in right away.
That is how it went, until Lisa Simpson released their leader, and doomed all of manknid to live in the ocean.
A companion is not the same as a satellite. That's all. A companion describes a similar orbit as another body. The Earth's moons have, necessarily, a slightly different orbit from the Earth if you plot them.
-- -
I am made of meat.
Re:Confused...
by
abhinavnath
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· Score: 3, Interesting
I understand the difference between a satellite and a companion. However Cruithne and this body both follow spiral orbits in resonance with the Earth. Neither body orbits the Earth directly. I wanted to know why 2002 AA29 was described as the "first ever" companion object found when 3753 Cruithne was discovered in 1997, and given the discoveries of 1998 UP1 and 2000 PH5.
Heh heh. It would have to be a honeymoon/swinger resort, because apparently it takes 3 people to have sex in space.
-- A deep unwavering belief is a sure sign you're missing something...
That plot's been used multiple times
by
billstewart
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· Score: 2
I haven't seen the particular tripe you're referring to (I'm assuming you're talking about a particular instantiation of Donaldson's Law* as opposed to the whole SF genre), but there have been a number of SF stories and novels using the "planet on the other side of the Sun where we can't see it" plot device. Sometimes it's named Nemesis, though that name has been used more seriously for Sol's hypothetical relatively-dark companion star.
* Donaldson's Law: Sturgeon was an optimist.
--
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Re:That plot's been used multiple times
by
nomadic
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· Score: 2
Hmm, interesting link, I didn't know Argon was written by a 16 year old. Kind of makes all the mocking unfair.
Re:Not quite a planet, eh?
by
Guppy06
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· Score: 3, Informative
"In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit."
Follow along in your copy of Principia Mathematica and repeat after me:
An object maintains linear velocity unless acted upon by an outside force.
Force of sun on asteroid: outside force Force of asteroid on sun: not involved
It doesn't matter whether the mass in question is you, a '57 buick or the Death Star. An object 1 AU away (on the average) from something with the mass of the sun orbits once every 365.2429 days, give or take.
Galileo figured out in the 17th cenutry that all objects reguardless of mass fall at the same acceleration. Where have you been in the past 350 years or so?
100 meters isn't very big. It'd be cheaper to ship that much stuff uphill ourselves rather than lassoing this one. Other nearby asteroids, such as Cruithne, would be more interesting possibilities, though I'd hate to have to fill out the Environmental Impact Report for potential hazards of mistakes....
--
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Famous last words...
by
vikstar
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· Score: 4, Funny
"it could be nudged into a permanent Earth orbit where it could be studied at greater length."
-- The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.
Re:Famous last words...
by
sczimme
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· Score: 2, Funny
"Hey y'all - watch this!"
-- I want to drag this out as long as possible. Bring me my protractor.
Re:Effect on Earth
by
nurightshu
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· Score: 4, Interesting
I'm a firm believer in astrology, and I think that this type of object might play some role. [...] Thought?
Apparently not on your end of the connection, there's not. Now, I know we're supposed to be respectful of everyone's beliefs, no matter how crackpot or unfounded they may be, but come on! The URL is "science.slashdot.org," not "stuff-not-subject-to-empirical-proof,reason,or-ex perimentation.slashdot.org". This is a discussion about an asteroid in companion orbit (apparently of the L4 and L5 LaGrange points; see above), and you're wondering what effect it would have if 2002 AA29 were in the fifth house while Jupiter and Venus are in ascendance.
In the immortal words of "Weird" Al Yankovic, "Now, you may find it inconceivable or at the least a bit unlikely that the relative positions of the planets and the stars could have some special deep significance that applies exclusively to only you." I do. 2002 AA29 has been conclusively proven to exist. Has the "like, influence of the planets, man" been subjected to the same rigorous standards?
Didn't think so. Thank you, please drive through.
-- They that would sacrifice their.sig space for that cliched Franklin quote deserve neither.
Re:Why the US will never switch to metric
by
weiyuent
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· Score: 5, Funny
1) Thousandths of an inch are useful in measuring machine tolerances, while millimeters are two gross and micrometers too fine.
Millimeters are two gross? As in 2 x 144?;-) I think you mean "too coarse".
2)Celcius is not fine grained enough to figure out how to dress for the weather, while Fahrenheit allows one to easily judge whether or not to wear a jacket.
You have got to be kidding me. Do you wear a hundred layers of tissue paper, peeling them off one by one at 1 Fahrenheit incremements? I've survived so far just by putting on a jacket when it get's close to freezing.
3) In the English System, force is the fundemental unit and mass is the derived unit, while in the metric system, mass is fundemental and force is derived. This works well for science and engineering, but Joe Sixpack thinks in terms of weight on earth -- pounds of force.
Oh please. So you're telling me that everyone who uses the metric system gets terribly confused when they have to speak in precise terms of mass vs. force? You must be denser *grin* than I thought.
Re:Interesting... but wrong
by
canadian_right
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· Score: 2
Earth, Sun, Asteroid - yup! thats three bodies.
So we won't get a nice simple elipse.
-- Anarchists never rule
Re:Why the US will never switch to metric
by
Tim+C
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· Score: 3, Informative
Imagine if we measured in Kelvin, though... that would be confusing!
Re:Why the US will never switch to metric
by
mpe
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· Score: 2
1) Thousandths of an inch are useful in measuring machine tolerances, while millimeters are two gross and micrometers too fine.
Since the second world war both the Imperial and US (English) inch have been defined as being exactly 25.4mm Prior to then these two inches were different enough that precision machine components would not fit. So in reality thousandths of an inch are 25.4 microns.
2) Celcius is not fine grained enough to figure out how to dress for the weather, while Fahrenheit allows one to easily judge whether or not to wear a jacket.
The weather forcast is always right, the weather never changes in a day, there is no variation in temperature over the forcast area? People were deciding to wear/not wear jackets long before any precision temperature scales were invented.
Re:Planetary defense system....
by
mpe
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· Score: 2
On a side note, shouldnt we be trying to go out, attach small effecient space engines to these fly bys and forcing them into orbit either around the earth or the moon to possibly be used one day to slingshot off at a more deadly threat?
If you can redirect asteroids into such orbit it is very easy to change such a system into a weapon of mass destruction. No changes of the hardware are needed. The asteroid dosn't care if it's in stable Earth orbit, unstable Earth orbit or goint to collide with Earth.
I am curious, though, if they say it's effectively a second moon, why are there no stories about it from 550AD? Or are there stories and we just thought of them as novas or other odd phenomenon? Even if it is 100 meters, I would think it would show up.
What matters is its optical magnitude. You cannot see a manmade structure of similar size on the surface of the Earth from orbit. Even a skyscraper which reflects considerably more light than an asteroid.
It is also intriguing since no 'trojans' have been discovered for the Earth and this could signal that we do in fact have some. Trojans are asteroids that occupy the 4th and 5th Lagrangian points about a larger body.
These are approximatly 1 AU from Earth. Hardly near...
(Jupiter has the most, due to its large mass).
What also matters is size and mass distrubution. The mathematics treats all objects as though all their mass is concentrated at a single point. Since planets and stars are not actually points Lagrange "points" are actually regions of space.
Because of the physics involved in a 2 body system where any additional bodies have negligible mass compared to the original 2, there are a few 'stable' points where the gravitational forces cancel out...these are known as Lagrangian points. L4 and L5 are co-orbital to the less-massive object (Jupiter, Earth, whatever).
There are 5 such points. L4 and L5 are co-orbital 60 degees ahead and behind the orbiting object.
Re:Why the US will never switch to metric
by
Casualposter
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· Score: 2, Interesting
How do you figure that Celsius is exactly as fine grained as Fahrenheit? Degrees Kelvin and Degrees Celsius are exactly the same size, but 1 degree F is smaller than one degree C.
Example: Freezing to Boiling on water is 32F to 212 F and 0 C to 100 C or 273 K to 373 K. Therefore, by simple math, there are 180 degrees F between the boiling and freezing of water, and only 100 degrees C or K for the same measurements. It would seem to me that the finer temperature scale is degrees F.
-- Creative Spelling Copyright (2002). May use without Persimmons
Guys, Galieo had a look at this one, once. Thinks about it. Objects of different masses accelerate at the same rate in a uniform gravitational field. The duct-tape anology is perfectly correct also.
It's more or less a modern version of an analogy Galieo used. Newton worked out the maths. The force on the smaller object is F=G*m*M/(d*d), from Newton's formula for gravity. From Newton's second law you get F=m*a. Thus m*a=G*m*M/(d*d). m, which is the smaller mass cancels, giving a=G*M/(d*d). N.B. an object is orbit is as much under acceleration as one being dropped from a tower.
Hint: why does a low earth orbit -- like the Space Shuttle's -- always take the same time? Orbital period depends only on the mass of the earth and the radius of the orbit, not of the satellite.
The gravitational force on the orbiting object does depend on its mass. But an orbit involves an acceleration. Newton's second law gives that F=ma or a=F/m. Where the force in question is gravity the force is directly proportional to the mass of the object being accelerated. A little basic algebra demonstrates that the mass of an object accelerated by gravity is not a factor in its acceleration. The major factor for an orbit of the shuttle is the distance between the shuttle and the Earth's centre of mass. The shuttle having gone from the Earth's surface makes negligable difference to the Earth's mass nor does the amount of matter which falls to the Earth from space daily. In the same way that calculating something in solar orbit does not require adjusting for the particles and photons the sun throws off. Planets gain mass and stars lose mass constantly, but it makes so little difference to the total mass of the bodies in question.
So why won't 2002 AA29 ever hit the earth? Do a google search on the Jovian Trojans. Or look up Lagrange Points. Or just consider the complexity of a three body system.
If it was near Earth you'd have a 4 body problem anyway.
Force of sun on asteroid: outside force
Force of asteroid on sun: not involved
Actually the force on the Sun is exactly the same as the force on the asteroid. Gravity is a symetrical force. When you have gravity acting between objects of very different mass you can ignore the effect of the force on the more massive object. Whilst the attraction between the sun and an asteroid causes the asteroid to orbit the sun it is several orders of magnitude too small to overcome the sun's inertia. Only when dealing with gravitational attraction between objects of similar mass does the symetical nature of gravity become relevent.
Galileo figured out in the 17th cenutry that all objects reguardless of mass fall at the same acceleration. Where have you been in the past 350 years or so?
In physics terms, falling and orbiting, due to gravity, are the same thing. Which is why objects in Earth orbit are said to be in "freefall". In both cases you have an object under gravitational acceleration from a much more massive object.
Think of orbits as though the object were constantly falling. The difference is, the direction in which they are falling is constantly changing.. at a rate that allows it to never lose or gain distance.
Assuming you have a circular orbit. Even though the speed of an object in a circular orbit is constant its velocity is not, since it is constantly changing direction. A change in velocity is called an "acceleration". The acceleration of any object is proportional to an external force exerted on it divided by the mass of the object being accelerated. Where an object is accelerated by gravity the force is proportional to the mass of the object. Thus the acceleration does not depend on the mass.
Now, the article says that the asteroid doesn't come closer than 3.6 million miles.... However, it'd be interesting to see any type of effects it may have environmentally, however minimal. Perhaps it may alter tides (albeit slightly) Also, be interesting to see if any significant events occured around 550AD....
This is a large rock, the gravitational effect it would have on the oceans is utterly minute compared with everthing else going on in them. Waving your hands about over the sea would apply more gravitational force.
Or maybe historically, it shaped events (much like comets before battles) as it probably would appear as a new brighter star in the sky.
The object simply appears to be a rock of around 100m size. Comets are bright because they emit dust and gas which both scatters sunlight and is converted to plasma by the solar wind. The dust clouds and tail surrounding a comet are huge as well.
In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit.
In other news, Galileo was wrong -- heavy objects DO fall faster than light objects.
Re:Why the US will never switch to metric
by
laertes
·
· Score: 2, Interesting
Consider a mercury thermometer. Say we put a Celcius scale up the left side and a Farenheit scale on the right. Now, say the temperature goes up; obviously, the mercury goes up too. Now, here's why you get to say the two scales are equally as fine-grained: the mercury goes up the same amount on the left as on the right. So the decimal digits will differ, but we just use more signifigant digits anyway (we have an unlimited number of them, get it?).
(To this post's grandparent) BTW, have you ever watched a weather report? They give temperatures in ranges (ie High 60's). With Celcius, the ranges will be tighter (ie 16C-17C), so I still don't understand your point.
But we'll still probably all be DEAD and NUKED into oblivion within a decade!
You kids today. Who are you afraid of? Iraq? North Korea? The Taliban? HA!
Back when I was a kid, we had a real reason to worry about being nuked. We were standing toe-to-toe with the Ruskies, each with a nuclear arsenal whose total destructive force measured in the GIGAtons. And, our President was a senile old coot who had once been upstaged by a chimpanzee! So don't talk to ME about being nuked.
--
Hey kids, there's only 5 days left 'til Yak Shaving Day!
Sounds like my brother...
by
kr4jb
·
· Score: 2, Funny
- is only about 100 metres wide
- never comes closer than 3.6 million miles to our planet
Sounds like my brother.
-- // Alan Porter
This object is easy to reach
by
mike449
·
· Score: 2
Massive amounts of fuel are necessary to change the orbit of a space probe so it differs sufficiently from the Earth orbit to reach other planets. If an object has an orbit similar to Earth, it is easy to reach. The spacecraft should be accelerated very slightly to change its orbit to coincide with the object.
Watch for falling rocks
by
rendermouse
·
· Score: 3, Funny
"Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length. "
Just what we need. Someone pushing huge space rocks closer to the planet to get a better look.
Have you never broken a microscope slide by zooming in too far?
--
"Follow your Bliss." -- Joseph Campbell
Re:I'd welcome an explanation of this.
by
Technician
·
· Score: 2
In regards to your last line, I can shed a little light. If it was just the object and the earth, your point is valid. There is no real place to borrow a boost to escape the orbit. However we have a moon orbiting the earth. If an object in an outer orbit aproaches as the moon is oposite the earth, as the moon orbits lower (shorter day) the moon will follow the object taking some of it's energy slowing it into the earth orbit where it no longer has the energy to escape. Later the moon will lead the object and boost it enough to escape. For an over simple view not to reality but easy to visualize, imagine an object in orbit passing between the earth and moon. The sweet spot where the pull from the earth and moon are the same will be a spot where gravity no longer pulls the object in an orbit. In that space the object will travel in a straight line (no gravity pull from the earth), not in an orbit path. This can get an object boosted to a higher orbit. On the next trip around (since it's still in a lower orbit) it again catches up to the moon. As it catches up to the moon, it picks up speed raising it's orbit more while slowing it's time around the earth. As it follows the moon, it get slingshot to a higher and even slower orbit (longer day)so it never catches the moon and hitting it but is instead slung out of orbit now to orbit the sun for a few years until the timing is right for the process to be reversed and the object drop back out of the sun orbit back into the earth orbit.
I hope this deceleration into orbit and re-acceleration back out explination works for you.
-- The truth shall set you free!
Lots of replies with the wrong explanation
by
f97tosc
·
· Score: 2
Of course, the part I don't get, *why* can't it hit the Earth? In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit
The first sentence is actually a very valid question. However, the question is not answered by pointing out the error of the second sentence, as a zillion posts have done by now.
After all, if the object has an orbit that is just infinitesimally different from Earth, one would think that it would hit us sooner or later. And would it not make sense that the object were attracted by Earth when it got somewhat closer?
The real reason that the object will never hit us has to do with complex three-body interactions (sun, earth, object) The motion of the smaller body is called libration: it repeatedly gains and falls back in its orbit relative to the larger body, but never approaches it. This situation exists in several other places in the solar system, for example the "Trojan asteroids", which orbit the Sun in the same orbit as Jupiter, but can never approach the giant planet very closely.
Maybe if the asteroid was shaped like, say, the Oregon Trail. Or the Great Wall. Or the Luxor. You can see all those from orbit.
Only if it were of similar size. This is something like 100 metres, which isn't very big at all. Even at closest approach this object is something like 7 times the moon's orbit away. You'd have trouble making out the great wall from that distance...
David Brin (Sci Fi Author) considers this in the universe his novels take place in. He postulates silicon/mechanical, energy, gas giant, oxygen (including humans and most of the species interacted with in the series), and a couple other life types that I cannot recall offhand. The various types do not interact normally, because they do not have much of a common frame of reference to comminicate with and/or do not compete much for resources.
He also has a reason for why Earth was not visited much by aliens... we were not at an 'easy access point' in the wormholes that most aliens use to travel around with.
I like science fiction that really tries to make explanations that cover all the bases.:-)
-- "I will trust Google to 'do no evil' until the founders no longer run it."
Hello Alphabet.
-
+/-one nautical mile is one arc minute (1/60th of 1/360th of the earth)...... extremely convenient for navigation, so much [so] that I doubt navigation would ever be changed to "metric".
One kilometre is 1/10,000 of the distance from the north/south pole to the equator. Much easier to count for us 10-fingered types.
-- OS Software is like love: The best way to make it grow is to give it away.
Slashdot Mirror
Can't make up your mind of which system to use, huh? :)
When men used to be men
Since it's not a planet, wouldn't it be more like a cousin than a brother.
Jonahweb.com has stuff.
They found my secret asteroid base! Now I'll have to move it again before I can continue my plans to take over the world!
Kierthos
Mr. Hu is not a ninja.
Wake me up when Earth's little sister is found, and you've got some decent JPEG's.
Is this truly the only Earth I can live on?
Jeez, havn't they found Counter-Earth yet?
"Sic Semper Tyrannosaurus Rex."
?-|||-----x<*))))><
No not really. It doesn't have enough mass to make a noticable difference.
jason
No one has seen what you have seen, and until that happens, we're all going to think that you're nuts. - Jack O'Neil
I thought we were up to what, four now?
"Sic Semper Tyrannosaurus Rex."
They claim it will be temporarily in earth orbit by 2600 AD. And then they go on to speculate on how important that would be to space exploration, possibly becoming the second object visited by astronauts.
If, in 600 years, we haven't sent astronauts to visit other planets, I have preemptively lost faith in the human race.
Come on, in 600 years we should have a pretty decent Mars colony going.
...
But despite detailed searches no one has yet found any Trojan objects near the Earth. Next come the inter-stellar port scans.
No, any object in the same orbital path travels the same velocity.
Think about it this way. If I have a heavy object and a light object orbiting at Earth's distance from the sun, by your hypothesis one will travel faster than the other. So if I duct-tape them together they should travel at a speed somewhere in-between the fast one and the slow one. But the taped-together object masses the sum of both smaller objects so it should travel faster. It can't travel both faster than and slower than its larger half, so the hypothesis can't be right.
JPL has a very nice tool for looking at the orbits of asteroids. Go to
http://neo.jpl.nasa.gov/orbits/
for the general case. For 2002AA29 in particular, you can use
http://neo.jpl.nasa.gov/cgi-bin/db?name=2002AA29&g roup=all&search=Search
Keep in mind that the orbital solution is based on only a short arc: only 28 days, about one twelfth of a complete revolution. Our estimates of the orbital parameters -- and behavior -- could change quite a bit over the next few months.
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
Life shrinks or expands in proportion to one's courage. - Anais Nin
Earth: "MOMMMMMMM! AA29 won't leave me alone! Please tell him to play on the other side of the solar system?!?"
Tal
"Study your math, kids. Key to the universe." -The Archangel Gabriel
Interesting physics, but Kepler's third law says:
The squares of the periods of the planets are proportional to the cubes of their semimajor axes
(http://home.cvc.org/science/kepler.htm).
So the mass of a planet has nothing to do with its orbital period (well, assuming it is small enough that it doesn't make the sun orbit it). So anything placed at Earth's distance from the sun and moving at the same speed would orbit the sun in the same path the Earth does regaurdless of its mass.
JET Program: see Japan, meet intere
The Earth of course revolves around the sun completing one revolution every year, but the Moon also revolves around the Earth in its own orbit.
Whether this new planet is actually a satellite of Earth is still to be determined. Also, a similar orbit does not mean that the climate is also known to be similar a priori.
The Earth's ecliptic orbit in summation with the Moon's orbit around the Earth means that the Moon must intersect the ecliptic; in fact, it will have to do so at two distinct points.
Has anyone found these nodal points for "Earth's Little Brother" yet? That's the true test of whether or not we will truly be affected by such circumstances.
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
I can see it now: "Thanks to a sucessful nudgeing, scientists have been able to determine that Asteroid AA29 is pretty much a big rock. In other news, bizarre tides continue to cause panic and destruction around the world tonight..."
_sig_ is away
if there are miniature people in miniature buildings driving miniature SUV's on it .. I'm packin my suitcase and leaving for another galaxy.
Or, barring that, could our planets swap all the SUVs?
"Old man yells at systemd"
roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit.
Wtf? Orbital velocity is a constant that depends only on the mass of the parent body, as long as the orbiting body is significantly lighter.
After all, geosynchronous satellites are all at approximately same height, although they have the same speed (to maintain synch), but different mass.
The formula for calculating orbits is:
T=2*pi*(a+h)/v
where T = period, a = radius of the parent body, h = orbit height, and v = satellite velocity, which can be calculated from:
v = sqrt(g/(a+h)),
where g is gravitational acceleration of the parent body.
You don't see the mass of the satellite anywhere here.
When men used to be men
Hint: why does a low earth orbit -- like the Space Shuttle's -- always take the same time? Orbital period depends only on the mass of the earth and the radius of the orbit, not of the satellite.
So why won't 2002 AA29 ever hit the earth? Do a google search on the Jovian Trojans. Or look up Lagrange Points. Or just consider the complexity of a three body system.
Unlimited growth == Cancer.
Can sny rocket scientists out there explain how two bodies in the same orbit can have different velocities, AND how the relative velocities can change over time?
They claim that for 90 odd years, the asteroid will accellerate ahead of us, to catch up with earth from behind, at which point it will fall back and we'll cath up with it. And then it repeats.
weird! I can't figure out how this is comes about, and the article didn't think it worth mentioning.
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
Uh, wouldn't that screw up the tidal system?
Yeah, but so what? Our species has a track record of fucking up the environment for the sake of profit. At least now we'd be fucking up the environment for the sake of science.
Yes, I'm kidding people. Sheesh...
GMD
watch this
I mean, come on...if we're as advanced as we seem to think we are, we should have been able to land something on it on jan 8, 2003.
Yeah, I know, that kind of thing is complex, but I feel we should have that spurious launch capability...god knows it would save us if we ever met something like what hit Jupiter a couple of years back.
-- Waht? Tehr's a preveiw buottn?
... now have the perfect candidate for their "free" state.
The reason this discovery is useful and more than 'whoop-de-doo' is because of what was mentioned in the end of the article: it is an extra-terrestrial body that is very close to the Earth. It would not be outside our reach to visit this object with current technology and learn more about the composition of asteroids and other minor planets in the solar system.
It is also intriguing since no 'trojans' have been discovered for the Earth and this could signal that we do in fact have some. Trojans are asteroids that occupy the 4th and 5th Lagrangian points about a larger body (Jupiter has the most, due to its large mass). Because of the physics involved in a 2 body system where any additional bodies have negligible mass compared to the original 2, there are a few 'stable' points where the gravitational forces cancel out...these are known as Lagrangian points. L4 and L5 are co-orbital to the less-massive object (Jupiter, Earth, whatever).
Although this object is not a trojan, since it has a horseshoe orbit and temporarily gets caught up in Earth's orbit, it suggests that there are bodies out there that could be trojans. Perhaps as our detection abilities progress, we will discover some Earth-trojans.
I drink to prepare for a fight; tonight I'm very prepared. -Soda Popinksi
"The Greeks built an immense wooden horse and Odysseus, Menelaus, and other warriors hid inside it. After leaving the horse at the gates of Troy, the Greek army sailed away. The Trojans thought the Greeks had given up and had left the horse as a gift."
The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.
Has anybody noticed how the BBC news is the best mainstream source for geeky stuff?
"That's no moon"
I wonder how hard it would be to pull that asteroid to earth orbit for mining or as an anchor to a space elevator, a la the [almost] original concept by Arthur C. Clarke (later designs use a man made anchor).
If we can mine useful materials, we could build some cool, big ass stuff probably cheaper than we would carry all that weight from the surface.
There are two kinds of people in the world: Those with good memory.
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects. So, how much do you think the sum of the masses of the sun and the Earth differs from the sum of the masses of the sun and 2002 AA29?
There are lots of explanations of horseshoe orbits on the web. Basically, if two objects share the same, or very similar, orbits, they are attracted to one another. That gravitational attraction drains kinetic energy from the leading object, and slightly adds kinetic energy to the trailing object.
The leading object, having lost energy, moves closer to the primary. Its year gets slightly shorter, and its actual velocity relative to the primary speeds up. Similarly, the trailing object moves farther away, and its year grows slightly longer.
So the leading objects closer orbit has it revolve around the Primary more quickly, and it will slowly move away from the trailing object. Eventually the leading object is exactly opposite from the trailing object. According to the BBC article, this takes 95 years.
Once the object that was leading is more than 180 degrees ahead in it orbit from the object that was trailing, their mutual attraction starts to add energy to its orbit, and raise it to a higher orbit. Similarly, the mutual attraction drains energy from the other object.
What we have just seen is the two objects trade places. The object that was the trailing object is now the trailing object.
It seems paradoxical that mutual attraction should tear the two object apart. Until you remember that the Sun's influence on the object's trajectories is much more important than their attraction to one another.
At least that is my understanding of the BBC's article.
How does this mechanism allow 2002 AA29 to be briefly captured by the Earth? I'd welcome an explanation of this.
"Do something man. Right now."
Finally!
Any body of rock that is orbiting the Sun and not another planet, is a minor planet if it is not a major planet like Mercury, or Jupiter. Asteroids are also known as minor planets.
Saskboy's blog is good. 9 out of 10 dentists agree.
No. It's too small. It's like passing a hand-size natural magnet 50 feet away from iron filings.
You are all fartheads.
Yeah, I know, that kind of thing is complex, but I feel we should have that spurious launch capability...god knows it would save us if we ever met something like what hit Jupiter a couple of years back.
I don't think having a spurious (false, unauthentic) launch ability would permit us to escape fiery death at the hands of a rogue shoemaker-levy-like object. Perhaps you mean extemporaneous. All jokes aside, it would be great to have a near-impromptu method for launching, but unfortunately missions are really expensive and require a great deal of planning. With the derth of funds going towards NASA these days, it should be expected that we won't have improvised launches anytime soon.
I drink to prepare for a fight; tonight I'm very prepared. -Soda Popinksi
No, it would be idiotic. The moon stores a huge amount of angular momentum. That's energy, folks. Let's see... we could waste a whole lot of energy trying to stop it, or we could leave it as it is so that years from now we may harness it usefully. Anyone read _Signal to Noise_, incidentally? Great book.
My deviantArt site
You keep on using that word. I dunna think it means what you think it means.
My deviantArt site
The phases that the moon goes through (waxing and waning and whatnot) has nothing to do with the rotation of the moon
Umm I'm pretty sure that he made the original comment in jest.. I doubt anyone who posts to slashdot is ignorant enough to think that the lunar cycles have anything to do with lunar rotation.
Which is exactly why we'd want to be forgetting Fox news.
Err... the force is proportional to the product of the two masses: F = -G M m / r^2; ... not the sum.
This post is strictly my own opinion and not necessarily that of my employer.
Comment removed based on user account deletion
If counter earth were there it would bash into it. And of course the counter-brother planet would bash into us at the same time. So no bizaro world. Bummer.
Some drink at the fountain of knowledge. Others just gargle.
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects.
:>
Maybe if you did have the equation for the gravitational attraction between two bodies nearby you'd realize that it is a function of the PRODUCT of the masses of the two objects.
F = (G x m1 x m2)/(r^2)
I drink to prepare for a fight; tonight I'm very prepared. -Soda Popinksi
I military aviation, we have all of that you mention plus, on the topographical maps, the horozontal distance is in kilometers (metric) and the vertical distance/elevation is in feet! The good thing is the altimiter is in feet too, but still...
Eve Fairbanks says I drive a hybrid!LOL
Imagine you have a cannon. You fire a cannonball out of it, and it follows a parabolic path until it hits the ground (Boom). Now, you get a more powerful cannon, and fire a cannonball even farther. In fact it's so powerful that the cannonball is traveling so fast horizontally that the ground is receding from it, due to the curvature of the Earth, faster than gravity is pulling it down to the Earth!
Tada! So the cannonball just keeps moving, around the Earth. It's in orbit.
I hope that explanation helps at least one person who was like me.
One proposed resolution is the Zookeeper Hypothesis, ie, they could have contacted us but are just waiting and watching for us to evolve, a la 2001.
If so, then wouldn't they want to put a probe near the Earth, which swoops down every few centuries or so for a close look, to see if any thing interesting has happened?
Here is Paul Wiegert's information on Cruithne, which has much of the same characteristic as this current space body, but his explanation actually makes sense for what appears to be a horseshoe orbit, when in reality it's only a horseshoe orbit from Earth's perspective, and is relatively sane looking when viewed off of the solar system plane.
IBM had PL/1, with syntax worse than JOSS,
And everywhere the language went, it was a total loss...
Guys, Galieo had a look at this one, once. Thinks about it. Objects of different masses accelerate at the same rate in a uniform gravitational field. The duct-tape anology is perfectly correct also.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
Neither your sig nor this sentence contains a paradox.
The enemies of Democracy are
Little brother? At its size, it is more like a booger of Earth.
It has a highly complicated orbit. It must be female.
Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length.
Better take out *a lot* of insurance before doing something like that.
Table-ized A.I.
That's only an explanation, not an argument. You're just -illustrating- that two objects would move at the same velocity, not -proving- it. So the other analogies were better. :)
The enemies of Democracy are
The contractors are sooooo screwed!
Eve Fairbanks says I drive a hybrid!LOL
'quite some time' is quite a bit longer than 12 months.
-
So just like that it shows up into our lives and we're meant to be all happy about it.
And I suppose we're expected to step in if Mercury or Venus start trying to take it's lunch money. And you know they're just gonna have a bigger brother as well. Don't we have enough problems with global warming and the like, without actively looking for trouble?
EXT. SPACE
2002 AA29:
You better not pick on me or gonna get my brother earth and he'll kick your ass!
MERCURY:
Oh yeah, I'd like to see him try.
EXT. SPACE - LATER
EARTH:
(sigh, to Mercury)
I heard you were giving my little brother shit.
(menacing)
What're you going to do about it now?
MERCURY:
Have you met my brother Jupiter?
From nowhere the gargantuan JUPITER appears.
EARTH:
Oh shit! Ay-Ay run!!!
When will we, the citizens of earth, ever learn that violence never solves anything.
the miniature X10 cameras in the miniature SUVs...
Gosh doesn't anyone read the SF of children's writer Eleanor Cameron?
She wrote "The Wonderful Flight to the Mushroom Planet", but in "Mr. Bass's Planetoid", she created a tiny asteroid that allowed the two young protagonists to view the Earth while having landed their spaceship on this asteroid.
Next thing you know, the BBC will report that we've discovered Lepton! Watch out Mushroom People, we're coming!
If telephones are outlawed, then only outlaws will have telephones.
What they're saying is they're scouring the space beyond the mesosphere for used condoms. Those things can wreak havoc on a satellite, let me tell you.
Because they're intelligent enough to stay away from this dump.
Hey, that's not funny. I heard that actually happened to some people a while back.
My deviantArt site
I noticed a few people wondering how this would affect our planetary tides, orbit, etc. This would NOT affect the earth at all. Hell, it wouldn't even make that big of a crater if it hit us (why do I think I'm going to get flamed for that?)
The thing is 100 meters wide. Imagine a 100 meter (300 foot) wide ball. If we just grabbed it and brought it to earth's surface (gently), it still wouldn't affect our tides at all. It's small enough to fit in a stadium. It's the size of a big hill. The point is that it wouldn't affect us at all.
Also, the reason it wasn't seen that long ago was that it was too far away and too small to see with the naked eye. (we could barely see it with a scope).
The best way to predict the future is to invent it.
Or rather, a question; who's to say that other intelligent life in the universe is anything like our species? The idea that they can and should colonize us, study us, or even visit us seems like the height of anthropocentric hubris. They might not be "flesh-and-blood." They might have a completely different relation to matter and energy as we understand it. They might live in water. They might have no interest in enslaving us or looting our precious natural resources.
How is this object considered a "companion" while Cruithne - Earth's "second moon" - is not?
Earth's Second Moon
2nd Moon Orbiting Earth Discovered
Google Search: Cruithne
Is there an astronomer in the house? Or anybody who could clarify this?
My other sig is also a
Now you will see the power of this FULLY FUNCTIONAL battle station!
Here you go. Fap away!
Heh heh. It would have to be a honeymoon/swinger resort, because apparently it takes 3 people to have sex in space.
A deep unwavering belief is a sure sign you're missing something...
* Donaldson's Law: Sturgeon was an optimist.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
"In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit."
Follow along in your copy of Principia Mathematica and repeat after me:
An object maintains linear velocity unless acted upon by an outside force.
Force of sun on asteroid: outside force
Force of asteroid on sun: not involved
It doesn't matter whether the mass in question is you, a '57 buick or the Death Star. An object 1 AU away (on the average) from something with the mass of the sun orbits once every 365.2429 days, give or take.
Galileo figured out in the 17th cenutry that all objects reguardless of mass fall at the same acceleration. Where have you been in the past 350 years or so?
100 meters isn't very big. It'd be cheaper to ship that much stuff uphill ourselves rather than lassoing this one. Other nearby asteroids, such as Cruithne, would be more interesting possibilities, though I'd hate to have to fill out the Environmental Impact Report for potential hazards of mistakes....
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
1) Move asteroid into permanent earth orbit
2) ?????
3) PROFIT!
paintball
"it could be nudged into a permanent Earth orbit where it could be studied at greater length."
The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.
I'm a firm believer in astrology, and I think that this type of object might play some role. [...] Thought?
Apparently not on your end of the connection, there's not. Now, I know we're supposed to be respectful of everyone's beliefs, no matter how crackpot or unfounded they may be, but come on! The URL is "science.slashdot.org," not "stuff-not-subject-to-empirical-proof,reason,or-ex perimentation.slashdot.org". This is a discussion about an asteroid in companion orbit (apparently of the L4 and L5 LaGrange points; see above), and you're wondering what effect it would have if 2002 AA29 were in the fifth house while Jupiter and Venus are in ascendance.
In the immortal words of "Weird" Al Yankovic, "Now, you may find it inconceivable or at the least a bit unlikely that the relative positions of the planets and the stars could have some special deep significance that applies exclusively to only you." I do. 2002 AA29 has been conclusively proven to exist. Has the "like, influence of the planets, man" been subjected to the same rigorous standards?
Didn't think so. Thank you, please drive through.
They that would sacrifice their
1) Thousandths of an inch are useful in measuring machine tolerances, while millimeters are two gross and micrometers too fine.
;-) I think you mean "too coarse".
Millimeters are two gross? As in 2 x 144?
2)Celcius is not fine grained enough to figure out how to dress for the weather, while Fahrenheit allows one to easily judge whether or not to wear a jacket.
You have got to be kidding me. Do you wear a hundred layers of tissue paper, peeling them off one by one at 1 Fahrenheit incremements? I've survived so far just by putting on a jacket when it get's close to freezing.
3) In the English System, force is the fundemental unit and mass is the derived unit, while in the metric system, mass is fundemental and force is derived. This works well for science and engineering, but Joe Sixpack thinks in terms of weight on earth -- pounds of force.
Oh please. So you're telling me that everyone who uses the metric system gets terribly confused when they have to speak in precise terms of mass vs. force? You must be denser *grin* than I thought.
So we won't get a nice simple elipse.
Anarchists never rule
Imagine if we measured in Kelvin, though... that would be confusing!
Please; just subtract 273:
>298K: t-shirt, shorts
293K-298K:t-shirt, jeans
etc...
It's official. Most of you are morons.
1) Thousandths of an inch are useful in measuring machine tolerances, while millimeters are two gross and micrometers too fine.
Since the second world war both the Imperial and US (English) inch have been defined as being exactly 25.4mm Prior to then these two inches were different enough that precision machine components would not fit. So in reality thousandths of an inch are 25.4 microns.
2) Celcius is not fine grained enough to figure out how to dress for the weather, while Fahrenheit allows one to easily judge whether or not to wear a jacket.
The weather forcast is always right, the weather never changes in a day, there is no variation in temperature over the forcast area? People were deciding to wear/not wear jackets long before any precision temperature scales were invented.
On a side note, shouldnt we be trying to go out, attach small effecient space engines to these fly bys and forcing them into orbit either around the earth or the moon to possibly be used one day to slingshot off at a more deadly threat?
If you can redirect asteroids into such orbit it is very easy to change such a system into a weapon of mass destruction.
No changes of the hardware are needed. The asteroid dosn't care if it's in stable Earth orbit, unstable Earth orbit or goint to collide with Earth.
Uh, wouldn't that screw up the tidal system?
Go wave your hand over the nearest sea. That has more affect in terms of gravity than an object this size in Earth orbit.
"Colonize?" "ANThropocentric?" Are you trying to tell us the universe isn't really filled with giant ants? That's a relief! ;-)
The Moore-Murphy Law: The number of things that will go wrong will double every 2 years.
I am curious, though, if they say it's effectively a second moon, why are there no stories about it from 550AD? Or are there stories and we just thought of them as novas or other odd phenomenon? Even if it is 100 meters, I would think it would show up.
What matters is its optical magnitude. You cannot see a manmade structure of similar size on the surface of the Earth from orbit. Even a skyscraper which reflects considerably more light than an asteroid.
It is also intriguing since no 'trojans' have been discovered for the Earth and this could signal that we do in fact have some. Trojans are asteroids that occupy the 4th and 5th Lagrangian points about a larger body.
These are approximatly 1 AU from Earth. Hardly near...
(Jupiter has the most, due to its large mass).
What also matters is size and mass distrubution. The mathematics treats all objects as though all their mass is concentrated at a single point. Since planets and stars are not actually points Lagrange "points" are actually regions of space.
Because of the physics involved in a 2 body system where any additional bodies have negligible mass compared to the original 2, there are a few 'stable' points where the gravitational forces cancel out...these are known as Lagrangian points. L4 and L5 are co-orbital to the less-massive object (Jupiter, Earth, whatever).
There are 5 such points. L4 and L5 are co-orbital 60 degees ahead and behind the orbiting object.
How do you figure that Celsius is exactly as fine grained as Fahrenheit? Degrees Kelvin and Degrees Celsius are exactly the same size, but 1 degree F is smaller than one degree C.
Example: Freezing to Boiling on water is 32F to 212 F and 0 C to 100 C or 273 K to 373 K. Therefore, by simple math, there are 180 degrees F between the boiling and freezing of water, and only 100 degrees C or K for the same measurements. It would seem to me that the finer temperature scale is degrees F.
Creative Spelling Copyright (2002). May use without Persimmons
Guys, Galieo had a look at this one, once. Thinks about it. Objects of different masses accelerate at the same rate in a uniform gravitational field. The duct-tape anology is perfectly correct also.
It's more or less a modern version of an analogy Galieo used. Newton worked out the maths. The force on the smaller object is F=G*m*M/(d*d), from Newton's formula for gravity. From Newton's second law you get F=m*a. Thus m*a=G*m*M/(d*d). m, which is the smaller mass cancels, giving a=G*M/(d*d).
N.B. an object is orbit is as much under acceleration as one being dropped from a tower.
Hint: why does a low earth orbit -- like the Space Shuttle's -- always take the same time? Orbital period depends only on the mass of the earth and the radius of the orbit, not of the satellite.
The gravitational force on the orbiting object does depend on its mass. But an orbit involves an acceleration. Newton's second law gives that F=ma or a=F/m. Where the force in question is gravity the force is directly proportional to the mass of the object being accelerated. A little basic algebra demonstrates that the mass of an object accelerated by gravity is not a factor in its acceleration.
The major factor for an orbit of the shuttle is the distance between the shuttle and the Earth's centre of mass. The shuttle having gone from the Earth's surface makes negligable difference to the Earth's mass nor does the amount of matter which falls to the Earth from space daily. In the same way that calculating something in solar orbit does not require adjusting for the particles and photons the sun throws off. Planets gain mass and stars lose mass constantly, but it makes so little difference to the total mass of the bodies in question.
So why won't 2002 AA29 ever hit the earth? Do a google search on the Jovian Trojans. Or look up Lagrange Points. Or just consider the complexity of a three body system.
If it was near Earth you'd have a 4 body problem anyway.
Oh wait, that's how the dumb Pollocks do it.
Please note, if you are a dumb Pollock, then I'm sorry, nobody should have to be a dumb Pollock...
Xaotik Designs
Force of sun on asteroid: outside force
Force of asteroid on sun: not involved
Actually the force on the Sun is exactly the same as the force on the asteroid. Gravity is a symetrical force. When you have gravity acting between objects of very different mass you can ignore the effect of the force on the more massive object. Whilst the attraction between the sun and an asteroid causes the asteroid to orbit the sun it is several orders of magnitude too small to overcome the sun's inertia. Only when dealing with gravitational attraction between objects of similar mass does the symetical nature of gravity become relevent.
Galileo figured out in the 17th cenutry that all objects reguardless of mass fall at the same acceleration. Where have you been in the past 350 years or so?
In physics terms, falling and orbiting, due to gravity, are the same thing. Which is why objects in Earth orbit are said to be in "freefall". In both cases you have an object under gravitational acceleration from a much more massive object.
Think of orbits as though the object were constantly falling. The difference is, the direction in which they are falling is constantly changing.. at a rate that allows it to never lose or gain distance.
Assuming you have a circular orbit. Even though the speed of an object in a circular orbit is constant its velocity is not, since it is constantly changing direction. A change in velocity is called an "acceleration". The acceleration of any object is proportional to an external force exerted on it divided by the mass of the object being accelerated. Where an object is accelerated by gravity the force is proportional to the mass of the object. Thus the acceleration does not depend on the mass.
Yeah, this one is lots of fun.
...
No, the orbital speed of the object around the sun won't depend on its mass until it gets so big that its mass is substantial compared to the Sun.
It would need to be something at least a similar order of magnitude to the mass of the Sun. Then working out orbits gets complicated.
Now, the article says that the asteroid doesn't come closer than 3.6 million miles.... However, it'd be interesting to see any type of effects it may have environmentally, however minimal. Perhaps it may alter tides (albeit slightly) Also, be interesting to see if any significant events occured around 550AD....
This is a large rock, the gravitational effect it would have on the oceans is utterly minute compared with everthing else going on in them. Waving your hands about over the sea would apply more gravitational force.
Or maybe historically, it shaped events (much like comets before battles) as it probably would appear as a new brighter star in the sky.
The object simply appears to be a rock of around 100m size. Comets are bright because they emit dust and gas which both scatters sunlight and is converted to plasma by the solar wind. The dust clouds and tail surrounding a comet are huge as well.
In other news, Galileo was wrong -- heavy objects DO fall faster than light objects.
(To this post's grandparent) BTW, have you ever watched a weather report? They give temperatures in ranges (ie High 60's). With Celcius, the ranges will be tighter (ie 16C-17C), so I still don't understand your point.
Yes, I'm still a junky. Are you still a bitch?
But we'll still probably all be DEAD and NUKED into oblivion within a decade!
You kids today. Who are you afraid of? Iraq? North Korea? The Taliban? HA!
Back when I was a kid, we had a real reason to worry about being nuked. We were standing toe-to-toe with the Ruskies, each with a nuclear arsenal whose total destructive force measured in the GIGAtons. And, our President was a senile old coot who had once been upstaged by a chimpanzee! So don't talk to ME about being nuked.
Hey kids, there's only 5 days left 'til Yak Shaving Day!
- is only about 100 metres wide
- never comes closer than 3.6 million miles to our planet
Sounds like my brother.
// Alan Porter
Massive amounts of fuel are necessary to change the orbit of a space probe so it differs sufficiently from the Earth orbit to reach other planets. If an object has an orbit similar to Earth, it is easy to reach. The spacecraft should be accelerated very slightly to change its orbit to coincide with the object.
"Some have speculated that it could be nudged into a permanent Earth orbit where it could be studied at greater length. "
Just what we need. Someone pushing huge space rocks closer to the planet to get a better look.
Have you never broken a microscope slide by zooming in too far?
"Follow your Bliss." -- Joseph Campbell
In regards to your last line, I can shed a little light. If it was just the object and the earth, your point is valid. There is no real place to borrow a boost to escape the orbit. However we have a moon orbiting the earth. If an object in an outer orbit aproaches as the moon is oposite the earth, as the moon orbits lower (shorter day) the moon will follow the object taking some of it's energy slowing it into the earth orbit where it no longer has the energy to escape. Later the moon will lead the object and boost it enough to escape.
For an over simple view not to reality but easy to visualize, imagine an object in orbit passing between the earth and moon. The sweet spot where the pull from the earth and moon are the same will be a spot where gravity no longer pulls the object in an orbit. In that space the object will travel in a straight line (no gravity pull from the earth), not in an orbit path. This can get an object boosted to a higher orbit.
On the next trip around (since it's still in a lower orbit) it again catches up to the moon. As it catches up to the moon, it picks up speed raising it's orbit more while slowing it's time around the earth. As it follows the moon, it get slingshot to a higher and even slower orbit (longer day)so it never catches the moon and hitting it but is instead slung out of orbit now to orbit the sun for a few years until the timing is right for the process to be reversed and the object drop back out of the sun orbit back into the earth orbit.
I hope this deceleration into orbit and re-acceleration back out explination works for you.
The truth shall set you free!
Of course, the part I don't get, *why* can't it hit the Earth? In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit
The first sentence is actually a very valid question. However, the question is not answered by pointing out the error of the second sentence, as a zillion posts have done by now.
After all, if the object has an orbit that is just infinitesimally different from Earth, one would think that it would hit us sooner or later. And would it not make sense that the object were attracted by Earth when it got somewhat closer?
The real reason that the object will never hit us has to do with complex three-body interactions (sun, earth, object) The motion of the smaller body is called libration: it repeatedly gains and falls back in its orbit relative to the larger body, but never approaches it. This situation exists in several other places in the solar system, for example the "Trojan asteroids", which orbit the Sun in the same orbit as Jupiter, but can never approach the giant planet very closely.
Tor
Maybe if the asteroid was shaped like, say, the Oregon Trail. Or the Great Wall. Or the Luxor. You can see all those from orbit.
Only if it were of similar size. This is something like 100 metres, which isn't very big at all. Even at closest approach this object is something like 7 times the moon's orbit away. You'd have trouble making out the great wall from that distance...
Apparently, it's impossible to push in space. They've tested this underwater in similar conditions, and apparently dolphins do the same thing.
A deep unwavering belief is a sure sign you're missing something...
I've never seen this before; thanks for the link. It's hilarious.
David Brin (Sci Fi Author) considers this in the universe his novels take place in. He postulates silicon/mechanical, energy, gas giant, oxygen (including humans and most of the species interacted with in the series), and a couple other life types that I cannot recall offhand. The various types do not interact normally, because they do not have much of a common frame of reference to comminicate with and/or do not compete much for resources.
:-)
He also has a reason for why Earth was not visited much by aliens... we were not at an 'easy access point' in the wormholes that most aliens use to travel around with.
I like science fiction that really tries to make explanations that cover all the bases.
"I will trust Google to 'do no evil' until the founders no longer run it." Hello Alphabet.
One kilometre is 1/10,000 of the distance from the north/south pole to the equator. Much easier to count for us 10-fingered types.
OS Software is like love: The best way to make it grow is to give it away.