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Earth's Second Moon
sbryant writes "According to the Daily Telegraph (free login required): the earth has a second moon called 'Cruithne', which was discovered by a British team.
The moon was previously thought to be an asteroid, but the experts now tell us that Cruithne, which is 3 miles across (4.8km), is in fact
a Trojan asteroid, and has an eccentric horseshoe orbit around Earth which takes 770 years to complete. "
such a long orbit around earth is bound to be unstable.
are they sure it will return to earth again? how many times did it pass here before?
Ballerinas have fins that you'll never find
Marvel comics always knew it was there!
BlackNova Traders
The Telegraph is as behind the times as ever. There was an SF novel published last year (Time by Stephen Baxter) which uses Cruithne as a plot device. The actual scientific announcement of Cruithne's somewhat unusual orbit was probably in 1998, but I'm not at home so can't check my references.
Are there actually people out there who believe this kind of news is true? (wish there werent)
UN: anoncoward PW: anoncoward
Many of you interested in anstronomy, or just the planets of the Solar System in general, might find this information very interesting. It's an account of other people who claimed to have discovered that Earth had a second moon.
I'm not trying to discredit the British team's discovery in any way, but it's still a very interesting read.
The main page of the site (called Nine Planets) is here.
when do I get to see two moons at once?
The only difference between an asteroid and a moon is whether it orbits the sun (asteroid) or another planet (moon).
There is good reason to suspect, for example, that the moons of Mars are captured asteroids, along with Charon (Pluto's moon).
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Clear, Dark Skies
as a devoted follower of the Zodiac, and how it affects me (i am totally aware of how my sign interacts with the planets to prevent me from obtaining any sort of good job or even a menial one) i am concerned... will this moon exert any pull over me as i try to appease the gods and the signs? will this alter my chances of attaining zen, although, being a devotee of astrology, i don't follow zen? should i worry that i was born under this moon and will never live long enough to see it return? this is too much for someone with no sense of self-determination!!!!!
sig not found
If memory serves me correctly, Crithne is an intricate part of the Sci-Fi novel, Time by Stephen Baxter. It mentions the horseshoe orbit and some other interesting things known about it. I didn't realise when I was reading it that the thing was for real. Very cool. You should check the book out if you're a Baxter fan. It's very good IMHO.
"Sir, I'd stake my reputation on it."
"Kryten, you haven't got a reputation."
something wicked this way comes...
For it was fortold, that when the two moons shall be seen together that the oceans would rise, and the sun would never come up again. So it is written.
Alternatively if we never see the two moons again might be for the same reason we never see Peter Parker and Spiderman or Bruce and Batman at the same time. When we are only "seeing" the dark side of the moon maybe it's getting into a slightly smaller dress and posing as the other one.
It's turtles all the way down.
Why do I get the feeling this has been spawned from the worst SF novel of 1999, by Steven Baxter? Really, this truly was an awful book, and the asteroid/moon/whatever was used as some silly plot device. Could it be that some moron actually mistook fiction for fact, or did Steven Baxter actually get ONE DAMN THING RIGHT in the whole book? I'd be surprised.
-- Minds are like parachutes... they work best when open.
Hey!
You get plenty of kids asking for the earth for their birthdays, but on mine I get a moon! Not bad for a start, is it?
:-)
Greg
Greg
(Inside a nuclear plant)
Aaaarrrggh! Run! The canary has mutated!
... works as always.
Not all of us are astrogeeks here. When does an orbiting body become a moon rather than as asteroid?
~~~~~~~~~
auntfloyd
see http://www.asteroid.yorku.ca/
At approximately 12:50 last night, some sorority girl somwhere screamed in disgust as a frat butt loomed threateningly from a car window. Scientists say the new moon is stationary and appears to have a random orbit. If confronted by the moon, stay calm and move slowly as it may attack. Don't try to feed it as we do not need domesticated moons in the area. Thank you.
It's MONDAS! Aiii! Kit Pedler was right! The cybermen are here! (And it's not too far off from when the script said, either.)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
http://www.asteroid.yorku.ca/
Scientists ignited renewed hopes for Extra-Terrestrial Cheese today, as they reported discovery of a second "moon" orbiting the earth. The asteriod, named Cruithne, was first discovered in 1986, but has only recently been subjected to detailed analysis of its highly eccentric orbit and dairyon emissions.
The asteroid will remain in it's orbit for at least 5,000 years. "That's plenty of time for proper ageing," said one astronomer. "And with a diameter of 5 kilometers, this asteroid could supply the earth with Space Cheese for centuries."
Thanks to whoever posted the article "Hidden Agenda".
Spaceballs!?
Oh shit. There goes the planet.
. . . thanks for posting it . . .
No more bad earthling jokes about how we only have one moon. Now all we need is warp direves and We'll be off the list of easiest planets to make fun of.
Born under the wobbling 'moon' Cruithne, you resonate with the sign of the Waffle. Your life is one of inconsistency, you bounce from job to job, relationship to relationship, never quite making that final connection. (On the other hand, you avoid conflict at all cost.) People see you as something of an enigma, following a different path than your peers. Since the conditions at the time of your birth will not come around again for another 700 years or so, you will never find contentment in this life. Hope that you are born again under a planet with a shorter orbit.
The Divine Creatrix in a Mortal Shell that stays Crunchy in Milk
The House Between - Original Sci-Fi Series
However, This link says this asteroid actually shares an orbit with the Earth around the sun.
Now, I know that this object has a rather unusual "orbit" of the Earth, but what exactly qualifies it as a bonafied Satellite rather than just a near Earth meteor?
"You ever have that feeling where you're not sure if you're dreaming or awake?"
"You spoony bard!" -Tellah
Its a space station!!!!!!!!!!!!!!
The thing is only a few KM's long, you probably won't be able to see it with the human eye. I am surprised it has maintained the orbit. 770 years to complete is pretty unusal, it must have a lengthly orbit..and if so then wouldn't other gravitational forces interact with it?
"Imagination is the only weapon in the war against reality." -Jules de Gautier
I've gone and higlighted it on my NEO map so you can all see where it is right now. (look near Venus). I presume this is the same object they're talking about.
It's not actually a moon of the earth, at least I wouldn't consider it a moon. Trojan objects aren't bound to their objects in the same way that moons are. Certainly the Earth's influence acts to stabilise the orbit, but if that's teh only criteria for an object being a moon then perhaps we should consider Pluto a Moon of Neptune since pluto is help in the 3:2 resonance with Neptune.
Oddly enough - the 1:1 resonance of trojan objects with respect to the Earth make it almost dynamically impossible for the object to ever become a true satellite of the Earth.
For those of you who don't know about the Pict people - the first inhabitants of our magical Isle - this might help:
Men are from Mars.
Women are from Venus.
But redheads are from a small, oddly-orbiting asteroid.
I don't know about you - but that explains an awful lot to me.
Oobeedoob: That's no moon.
Han Duet: Oh, sorry, let me hike these up!
The first pictures of the "new" moon were taken on December, 13th 1998... you don't believe? Look here! ;-)
- Pluto's low mass would make it difficult for it to capture an independent Charon.
- Charon has a very high mass relative to its parent body
- In fact, Charon and Pluto revolve about their relative center of mass about halfway between the center of Pluto and Pluto's surface
An interesting note (that would be I would be hard-pressed to claim as evidence supporting or countering my claim that Charon was not captured by Pluto) is that during Pluto's summer, its atmosphere encompasses Charon. It's so thin, though, that it doesn't affect Charon's orbit. During Pluto's autumn, the atmosphere "snows-out", and it won't have any atmosphere during winter. This is one of the reasons why launching a Pluto Fast Flyby was such a hot item a few years back -- they wanted to be able to study the atmosphere before it snowed-out. Now, it's not likely a probe will be able to do the flyby in time, but we can always hope & vote.Christopher A. Bohn
cb
Oooh! What does this button do!?
What type of cheese is this moon made up of. Is there a man on this moon? Will it ever have an eclipse? Will it have a blue moon? Will there be strange cults that only sleep every 770 years. What will happen to the nocturnal animals? What are the answers to these questions?
It's a numbered asteroid (3753) so the orbit is well-determined. Right now it's within 60 degrees of the Sun so that's a little challenging (but Venus is always within 47, Mercury 17ish, so that gives some perspective).
According to the Minor Planet Center it's presently at magnitude 16.2 in Scutum (approx R.A. 18h 34m, Dec. -14 11', but of course that's changing fairly quickly), with a solar distance of 1.205 AU and a distance from Earth of 0.56 AU. It has a diameter of about 17.5 km.
Since it's in Scutum, that means it's also in the Milky Way so the chances of there being few 16th magnitude stars nearby is well, astronomical! :-)
You can get up to date positions, etc. from the website listed above. Please be gentle - it's not a terribly fast server, and a lot of dedicated amateurs/professionals rely on it being available!
The orbit is a series of spiraling loops that form an overlapping horseshoe, with the Earth in the overlap. This orbital pattern therefore revolves around Sol along with Earth. Very strange, and pretty unusual (actual rarity is difficult to establish).
Here are some decent drawings and explanations of the phenomenon.
Powers&8^]
I remember reading _Asimov on Astronomy_ many times as a kid. Here's what I remember from one of his articles:
Anyway, as I read it, this asteroid is not a true moon in the sense of being a satellite of our planet. It still revolves around the sun. However, it is in a gravitational relationship with Terra, as our Luna is. In that sense I suppose it is "a moon".
I think in that same book, maybe even that article, Asimov discussed the Trojan satellites. At that point I don't think anyone had discovered any for earth, but dust clouds were detected in the L4 and L5 positions.
Astronomy is only a neglected hobby of mine, so I may not be totally correct. (I almost got a minor in it, but that's been years ago.)
Constitutionally Correct
Things like this have always fascinated me, I wish that I had more free time to spend learning about astronomy.
A couple of years ago, I bought a set of Cosmos video tapes (the old Carl Sagan show). One episode discussed the creation of the universe and the origins of all the elements, etc. He made one quote that summed up my beliefs... "We are Star Stuff". Of course, I am not an astronomer nor an extert in nuclear physics, so I apologize in advance if I offend anyone (I have degrees in Civil Engineering).
Sagan talked about fusion and so forth as well as how gold and other heavier elements are created by exploding super novas (as opposed to champagne super novas ). There is a certain simplistic beauty in the life of a star. It spends billions of years fusing hydrogen molecules into helium then in its dying days, it squeezes the helium molecules into other elements and in a spectacular "swan song" it explodes, seeding space with the basic building blocks of everything around us.
I have often wished that I had enough time to research the parallels between astronomy and various religious beliefs. I think that there are some interesting things that can be concluded from that sort of research.
Cypherpunk / Cypherpunk works.
You know what I hate?
THE MOON!
Turn that damn thing off. I'm trying to sleep.
No, that's not a trojan satellite. A trojan satellite shows up in a place where we would *expect* a satellite, and therefore send probes and astronauts to explore it. It thus gains vital information about us, steals our technology, and uses our DNA to create an army of clones.
They are a serious security threat. The first probe to an apparent sattellite should send a series of ^D to close any trojans before landing.
:)
...and NASA has to keep track of nearly all of it because to an astronaut space walking, even a pebble can be deadly when it hits him at 13km/sec traveling along it's counterdirectional Earth orbit. I recall a plot of the earth showing all known objects of 10g and up orbiting the earth. The earth looked like it had a swarm of bugs around it.
It has been a well known fact that there are dust clouds at the LeGrange points with the earth/moon system. I remember reading pieces about this in the early 1970s and I suspect that there were even earlier ones. Because such points form a potential energy well, random cruft collects there. However, for anything to be called a true moon, I would propose the following tests: 1) Is it bigger than a breadbox? 2) Is the orbit stable over several million years. The second is true with the dust clouds, and the first is true with this object. Both are not true with either this object or the dust clouds. Not to detract from the research which has more to do with the probablility of becoming toast from an asteroid collision and is well done, but a second moon? I think not.
At the point where it is closest to Earth is it inside or outside Luna's orbit? I am wondering about the arabic symbol of the cresent moon with a star between the horns. Something that has been conjectured as "fantasy" or as asteroid strike. Now I wonder if ir was Cruithne passing in front of the dark side of the moon. I'd guess it would pass far outside Lunar orbit. However this is just the kind of stuff that shows the ancient world wasn't as backward as many in science would believe.
It's CHIBIUSA! :P
At its closest approach it is about .1 AU from Earth, which is quite a bit more than the mean Earth-Moon distance of 3.8e5 km. Additionally, it never would pass *between* the Earth and Moon since at the closest approach it is almost directly below the Earth's south pole.
Intersting thought, though.
Admit nothing, deny everything and make counter-accusations.
entitled More Moons Arround Earth? It's Not So Loony
no message.
hmmm, does this mean that love songs will need to be updated?
...
<music>
When the moons hit your eyes like
<music&/gt;
Free as in "the Truth shall set you..."
It might also be that there are several such "Troyan" asteroids, so I'm not totally sure that this is the same one.
I think the orbit was calculated by Seppo Mikkola in Tuorla Observatory, in University of Turku, Finland. But I'm not too sure about this, the following article seems to have two Finnish authors, but the primary author may well be British. It may be that the observations were British, or something like that.
See:
*Wiegert, P.A., *Innanen, K.A. and Mikkola, S. 1997: The Earth companion asteroid 3753 (1986 TO) - Nature 387: 685--686.
This cluster wasn't hard to explain - the "three body problem" can't be analytically solved for the general case, but it can be easily solved for cases where M1 >= M2 >> M3. This solution shows five points there the gravitational attraction of the two large bodies balance. IIRC all of these points are "stable," but objects can orbit those points for billions of years before friction with the solar wind, gravitational attraction from other objects, etc., cause the object to return to a normal orbit.
The five Lagrange points are named L1-L5. As I recall, if M1 >> M2 then
L1 = on M1-M2 line, opposite of M2 (e.g., "counter-earth")
L2 = on M1-M2 line, between M1 and M2, (e.g., the solar observer satellite)
L3 = on M1-M2 line, beyond M2
L4 = 60 degrees ahead of M2 on M2's orbit
L5 = 60 degrees behind M2 on M2's orbit
Since it's been twenty years since I thought about this, I might have L1-L3 permuted and L4-L5 reversed.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
You'd think the Electronic Telegraphers would have heard about Web Usability Research (Alertbox July 1999).
CowboyNeal for president!
"Hit any user to continue."
The trojan asteroids are found in the same orbit as Jupiter. The orbit at a stable gravity well formed by the interaction between Jupiter and the Sun. They follow Jupiter (or maybe lead, I can't quite remember) in the same orbit one sixth of the way around the sun. Trojan asteroids are classified solely by their pecular orbit, so that a former trojan asteroid orbiting Earth would no longer be a trojan asteroid.
The concept of a "horseshoe" orbit is laughable. If it is in a closed orbit, that orbit must be an ellipse (see Kepler's first Law). A horseshoe is open ended, and while open ended orbits do exist, the object would only pass by the earth once in the orbit, achieve escape velocity, and never return.
In other words this article, and yea verily this Slashdot post, makes no sense whatsoever.
The object was discovered by a British team, but it's "satellite" nature was not known until a Canadian team performed the analysis (contrary to an earlier posting which credited one at a... Turkish university?).
Alors, we have a co-discovery... unreported, as is usual for matters of Canadian pride. But astronomy and other such international sciences is to be about the high purpose of fact and truth and the extension of knowledge's frontiers, not nationality or whatsoever nation a research happens to be working in. Consider all the discoveries by foreign (non-Chilean) researchers in Chile's Atacama Desert...
By the by, there is some interest among a select band of Canadians to launch a probe to the asteroid...
*+]Strange moods are the validation of the universe.[+*
--
Time is Nature's way of keeping everything from happening at once... the bitch.
- The orbit is inclined 20 degrees to Earth's. Change-of-plane maneuvers are very costly in terms of propellant.
- Being so close to the Sun, there is a smaller likelihood of Cruithne having deposits of the essentials for life-support: water, ammonia or methane ices. These would make it more attractive to set up shop there, because resupply costs would be drastically reduced.
As it is, we're probably better off looking for something like an extinct comet nucleus, regardless of its orbit, if we want to set up a space station far from Earth.--
Time is Nature's way of keeping everything from happening at once... the bitch.
--
Time is Nature's way of keeping everything from happening at once... the bitch.
Sorry, 'bout that, folks. It's just one o'me Big Hairless Balls, floatin' up in space.
Only the Ball-sack can save this Great Country.
Horseshoe orbits are not exactly unique. Methinks the British Government's attention to the near-earth asteroid problem caused this group to smell the grant money.
Here are some more links on Asteroids /Arcade/aster.html
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http://markn.users.netlink.co.uk
http://www.atarihq.com/2678/revi ews/asteroids.html
http://www.funescape.com/games/as teroids/main.htm - Java required.
-M
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Note also that there is a difference between "equilibrium" and "stability". Equilibrium just means that there exists a static solution to the equations of motion (albeit static in a rotating frame of reference in this case). Stable means that the static solution, if perturbed, will return to the equilibrium instead of drifting off into some dynamic orbit. The L1-L3 points are stable to perturbations in one direction (the tangential, if I recall), but they are unstable to perturbations in the other direction. Consequently, one doesn't expect to find long-lived orbits at these locations. The L4 and L5 equilibria are stable against all perturbations, so one might expect to find objects in long lived orbits at these locations, like the Trojan asteroids, for instance.
The original poster's confusion arose because the earth has two sets of Lagrange points associated with it. One comes from the earth-moon system (in which the earth is M1 and the moon is M2), and the other comes from the earth-sun system (M1==sun, M2==earth). An object at L4 or L5 in the earth-moon system would appear to orbit the earth in synch with the moon, while an object at an earth-sun lagrange point would appear to orbit the sun in synch with the earth. So, it's a little far-fetched to call an object at the earth-sun Lagrange points a "second moon", although such an object is in some sense more deeply associated with the earth than an object in some random solar orbit.
Finally, one should remember that the Lagrange points are solutions of the restricted 3-body problem which presumes that there are only three bodies in the system. Obviously, that isn't the case in our solar system. For instance, I've seen people argue that the earth-moon L4 and L5 points aren't really stable because of the sun's influence. Similarly, the lagrange points between the sun and most of the outer planets are thought to be disrupted by Jupiter's gravity. Consequently, I wouldn't be surprised if Venus' gravity had a tendency to destabilize the earth-sun Lagrange points, resulting in objects trapped there eventually escaping into regular solar orbits.
-r
The story is here
Heh, just being a proper anoncoward, I thought that I'd point out that another reason that the atmosphere "doesn't affect Charon's orbit" is that the two bodies are syncronous in orbit and rotation. Kinda like how the same side of the moon always faces the earth, the same side of Charon always faces Pluto, and as a bonus, the same side of Pluto also always faces Charon. So there's no relative motion bewtween the two. Think of it as a nonrotating satellite in geosynchronous orbit. Just another Anonymous Coward!
are they those things I see on the street in hollywood?
NBC 4, Washington DC area closings.
Slashdot: Science: Marriot to Open Resort on Cruithne
Great, the way he said "the earth now has a second moon. Its name is Cruithne. Luv dat.
Where is my mind?
Check out Project Upper/Mute, an all-around awesome compiler fra
http://www.register.com/whois-results.cgi?domain=c ruithne.com
Jeez.
- You still have the Zodiacal light fogging your pictures of nebulae; to get away from that, you need to go further from the Sun.
- You can't see much more of the Sun from a 20-degree inclined orbit. For that you really want a polar orbit. If you want to see solar flares and prominences from a different angle, you'd want to be at the Earth-Sun L4 or L5 point instead of on Cruithne, which varies its angular separation from the Earth-Sun line throughout the year.
- You can't see much more of the sky from Cruithne than you can from the Moon's L4 or L5 point, and it's a lot faster to get data back from the shorter distance.
- Last and most significant: what kind of observatory needs to be gotten away from Earth and put on a rock somewhere out in the middle of nowhere, so that you can still only see the half of the sky it doesn't block? Why not a free-flying probe?
An observatory which is best suited to Cruithne than somewhere else would have to have some very specialized requirements. I can't think of anything that has requirements remotely like that. Note: I am not an astronomer.--
Time is Nature's way of keeping everything from happening at once... the bitch.
ok, lets call every rock in space a moon to earth to attract press and make someone very famous. Don't we have enough problems on earth to deal with: population, environment, technology I am not against the space related research, but common, our life is getting already filled with information spam and there are far more exciting news reporters can find than some stupid rock that happen to have an orbit around earth and god knows if tommorow it wont even be there, as long as it isn't a threat to earth.
Here ya go.
1 1&rtmo=VMM83qJK&atmo=YYk7k37p&pg=/et/00/ 1/25/nmoon25.html
http://www.telegraph.co.uk:80/et?ac=0020682315192
--
- Sean
It's a fine line between trolling and karma-whoring... and I think I just crossed it.
- Sean
... preparing to gun down the earth to punish all those evil DVD pirates!
So both Cruithne and Moon trace out a repeatable path with respect to the Earth, but both can be considered to really orbit the Sun.
--Neal
--Neal
Go IETF!
Does this mean that Russia can beat JFK's challenge of the early '60s to send men to the moon first?
You still have a chance, Russia! RUN! RUN!
Rob, I submitted the same story with a whole lot more useful links and detail in it.
If you wanted to post it yourself, that's fine; but at least include the links, to make the story more useful to folks.
Technically...doesn't every peice of shit that we put into orbit qualify as a moon?
To be serious here, what if some country attached a device to slowly push this thing into the earth? Carl Sagan argued _against_ anti-asteroid devices for fear that they could be used in this way as a weapon. I say we destroy it into space dust somehow or send it into the sun before some crazy enemy develops the technology to go and fetch it.
We ought to do this at every site that requires free registration:
Username: Slashdot (case-sensitive)
Password: Slashdot
--
Patrick Doyle
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
space.com has an article about Cruithne as a moon, "More Moons Around Earth? It's Not So Loony", from October 29...
Deven
"Simple things should be simple, and complex things should be possible." - Alan Kay
Here is the article that the Telegraph seems to have based their article off of http://www.space.c om/science/solarsystem/second_moon_991029.html More informative, and no registration necessary.
see Subject.
now we need to go OSS in diesel cars
yes, they've been going downhill for a while, it seems. The readers have been getting less community oriented and more -i'm-smart-and you-are-dumb message oriented.
that they attribute stories top whoever they like better, as in they play favorites with people, or something. Definitely something that makes you lose a lot of respect, isn't it? Seems like , hmmmm, alittle immature? Perhaps someday Slashdot will begin to act professional.
Here's an applet simulating Cruithne's orbit for as long as you care to watch it. I don't know how accurate it is, but it does show the horseshoe orbit and start to fall apart around 5000 years just as the article said. http://burtleburtle.net/bob/physics/cruithne.html