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Earth Travel On Time, Again
burgburgburg writes "The NY Times has an interesting article about a rather puzzling phenomena: for the fifth year in a row, the Earth's travel through space is right on time. The rate that the Earth travels through space has slowed ever so slightly for millenia. To compensate for this, since 1972, scientists have added a "leap second" at the end of each year. The problem: Since 1999, the Earth has been on time. The recognition of a need for a leap second was an unintended consequence of the invention of the atomic clock. Suggested reasons for the unexpected punctuality: the tides, weather and changes in the Earth's core."
The Earth knows that we're watching now, so it's taking extra care to be punctual...
Suggested reasons for the unexpected punctuality: the tides, weather and changes in the Earth's core.
No. God just likes to screw with us.
Scientists: Earth Travel Time on Schedule Scientists Say Earth Is on Schedule in Regards to Rate at Which It Travels Through Space
The Associated Press
BOULDER, Colo. Dec. 30 -- In a phenomenon that has scientists puzzled, the Earth is right on schedule for a fifth straight year. Experts agree that the rate at which the Earth travels through space has slowed ever so slightly for millennia. To make the world's official time agree with where the Earth actually is in space, scientists in 1972 started adding an extra "leap second" on the last day of the year.
For 28 years, scientists repeated the procedure. But in 1999, they discovered the Earth was no longer lagging behind.
At the National Institute for Science and Technology in Boulder, spokesman Fred McGehan said most scientists agree the Earth's orbit around the sun has been gradually slowing for millennia. But he said they don't have a good explanation for why it's suddenly on schedule.
Possible explanations include the tides, weather and changes in the Earth's core, he said.
The leap second was an unexpected consequence of the 1955 invention of the atomic clock, which use the electromagnetic radiation emanated by Cesium atoms to measure time. It is extremely reliable.
Atomic-based Coordinated Universal Time was implemented in 1972, superseding the astronomically determined Greenwich Mean Time.
Leap seconds can be a big deal, affecting everything from communication, navigation and air traffic control systems to the computers that link global financial markets.
Just add {In Space!} to anything.
Hmmm... don't think that'll help my procrastination.
.... we can speed it back up again.
Let's do it!
NIST
We decided that for a change this holiday we'd work on big iron - the earth. Using polar cap cooling and using two atoms instead of one in the atomic clock, we managed to accelerate the earth by 1 second. System is perfectly stable. Except in California. And Iran.
www.voiceofthehive.com - Beekeeping and Honeybees for those who don't.
According to http://tycho.usno.navy.mil/leapsec.html leap seconds compensate for changes in the earths rotational speed not the earths orbital speed.
Don't you guys remember back in 1999 when the moon blasted out of earth's orbit? That would probably explain the change.
I live ze unknown. I love ze unknown. I am ze unknown.
OK so help me out here. Pardon the pun, but how on earth do they figure out that the earth is in the exact same position as it was a 'year' ago? Do they use the background of stars, or some other mechanism? How can they reduce the error in such a measurement so that they can be sure that a second has been 'lost'?
I really could have used that extra second of sleep after partying late on new years eve.
before the atomic clock the Earth was always on time.
It's good to know that the fudge factor isn't always necessary too, what with a leap second occurring every year at some point the slop has to be soaked up in the system. Were the powers that be planning to save up a leap day? If they had, where would they have put it? Frankly, just letting the extra second add onto the end of the year and letting 43200 years swap noon and midnight would have been an interesting social experiment. Assuming mankind hasn't destroyed itself by then, of course.
The leap second is added to compensate for the slowing in earth's rotation, not its motion around the sun.
It is somewhat odd that the rotation has stopped slowing down. Some have speculated that as more and larger dams are built, creating large lakes far from the equator, that there's a net movement of mass closer to the axis -- causing the earth's rotation to increase in speed slightly.
On the other hand, global warming and the melting icecaps and warming oceans should move mass away from the axis, slowing down rotation.
It will be very interesting to see what happens over the next few years. I'd be curious if there's any relationship between the non-slowing of the earth's rotation and the decrease in the earth's magnetic field, mentioned in Slashdot a couple of weeks ago.
thad
I love Mondays. On a Monday, anything is possible.
Now there's one less excuse the airlines can claim for why my flight was late.
Kevin Fox
If all the chinese jumped off a chair at once, would it affect the earth? Original answer from StraightDope is here
Now that we've established that the article mistakenly talked about annual rotation instead of daily rotation, it seems plausable that a smaller rotational intertia is to credit.
If the core settled down even a tiny bit, so heavier elements rested slightly closer to the core, the planet's axial rotation would speed up like an ice skater pulling in their arms.
Alternatively, the wearing down of mountains (buildings?) could have the same effect.
If the Earth is speeding up, perhaps the terrorists have already won.
Maybe that's why they're all carrying almanacs!
Kevin Fox
I really should've taken the optimistic view that I'd feel better new year's morning from not spending as much time partying the previous night.
There is a very comprehensive reference of currently used time standards over at wolfram research site. It came up yesterday while I was trying to figure out the difference between Universal Time (UT) and Coordinated Universal Time (UTC). In the last link I believe you will find that "Earth's rotation is irregular at the 0.1 second level" along with a diagram of the errors so far.
I'm the leader of a Terrorist organization known as FART. Over the past few years Fuck Anal Retentive Timekeepers (FART) has led millions of disenfranchised Timex employees in a quest to change time! Yes, every morning and night (corresponding with sunrise and sunset), we face our asses westward and let our flatulence fly!
It's good to see our efforts to fuck with those atomic timekeeping twits succeeding!
The IERS has a plot showing how the length of day has decreased over the past few years. Curiously, the current phase of accelerated rotation of the crust began right around the time we started adding leap seconds to UTC.
It seems to me that physicists assume that their atomic clocks keep perfect time. But what if they don't? What if some key physical constants are changing in our neck of the universe. As an engineer I have found that most physical constants aren't (everything is a function of everything, its just an matter of the coefficient). In the case of the atomic clocks, a change of only 32 parts per billion would change the timebase by one second per year. Perhaps a particularly large, long-wavelength gravity wave has stretched spacetime and changed the clocks? Perhaps the four fundamental forces oscillate in undiscovered ways?
IANAP, so perhaps a professional could explain why the atomic clocks must be right -- why a 32 ppb variation in them is impossible (i.e. would manifest itself in other more obvious ways).
Two wrongs don't make a right, but three lefts do.
Just a thought and I know it's a miniscule mass by comparrison but we have sent some of Earth's mass to the Earth Sun L1 lagrange point which should slightly speed our orbit shouldn't it. The dates may coincide, it was launched in 95 but when it reached it's current orbit is unclear, some time towards the end of 1998 seems to be when some the instruments were first switched on. The on orbit dry mass of SOHO is 1350 kg.
So how about some back of the envelope calculations. How much mass at the Earth Sun L1 Lagrange point would it take to influence our orbit by one second per year?
I fully expect to be out by several orders of magnitude but can anyone answer?
The World of Astronomy site at Wolfram.com is a bit out of date and does not include the most recent changes in time scales. I recommend this page which describes the history of various time scales.
I thought they fixed that core problem a few years back by blowing the shit out of it with a bunch of nukes! I saw a documentary on this recently.
You got it backwards. The "leap second" was needed because the Earth *was* taking a little longer. For some reason it has stopped being slow by a second. If anything, its the Democrats trying to get Bush out of office a little sooner.
They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty.
Ben
Learn all about it at: http://www.democraticunderground.com/discuss/duboa rd.php?az=show_topics&forum=104
----- Indecision is the key to flexibility.
One second per year is about 32 parts per billion. Changing the rotation of the Earth by that amount could be accomplished by moving approximately 8260 cubic miles of "Earth" (i.e., material with the same average density as the planet) from the equator to the poles. Moving the material to the mid-latitudes would require moving more material to create the same rotational speed change. For example, we could move about 28,000 cubic miles of Earth from the equator to the 45 degree latitude belt.
28,000 cubic miles of Earth seems like a lot until you spread it out around the Earth. If it were removed from a 1000 mile wide band around the equator, it would be only 6 feet thick. But this still seems like a lot to me because it would have to include changing the mean sea level by 6 feet too and this would be very detectable from orbiting altimeters such as TOPEX.
Hmmm.... Either I've done these calculations incorrectly, or a great deal of material has been moved, or somebody hasn't published their data on changes in the planet's shape.
Two wrongs don't make a right, but three lefts do.
which is the year that this week falls into, and according to ISO standards the 1st week of the new year is the week that contains the first thursdays in the new year.....
so welcome to week 1 of 2004
Tidal slowing is also magnitudes more important than anything you'd see from mountain building, earthquakes, or any other surface phenomenon. The earth is BIG. But tides take out a LOT of energy. Tides are the major reason the Earth's rotational period slows over geological time.
So right now, the Earth is not slowing; this must mean a shorter-acting phenomenon is supplying the rotational energy that the tides normally suck out. Again, there is only one thing big enough -- turbulence in the Earth's liquid core. Like the Earth itself the core is BIG so little changes in the fluid flow there can actually affect the Earth noticeably, and that flow is known to be chaotic -- because the magnetic field caused by that flow reverses periodically.
My money would be on a near-term magnetic field polarity reversal. Of course "near term" probably still means it will be ten thousand years before it's a problem. Sucks to be a man-made satellite, though, especially when flying over the South Atlantic, an area where the Earth's magnetic field is already starting to do strange things.
Brackets contain world's first nanosig, highly magnified:[.]
If the Earth is assumed to be a homogeneous sphere and the rotational axis is assumed to be the straight line passing through the north and south geographic poles, the moment of inertia of the Earth is I = MR^2 where M is the total mass of the Earth and R is its radius. The kinetic energy of a rotating Earth is given by K = 1/2 I w^2, where w is the angular velocity.
The energy associated with a 1-second shorter-than-expected day is equivalent to an extra 1.6e22 Joules of energy or 40 times the annual energy consumption of mankind (DoE 1999). The matlab script is here.
Michael.
Linux : Mac
Well, I suppose Jupiter sacked Atlas for his continual tardiness and the new God is still all gung ho about the promotion to the new job. Eventually he'll get tired too...
Oh well, what the hell...
Global dimming.
To slow down in its orbit, it has to get farther from the sun (otherwise it'd fall in closer to the sun, and it doesn't).
Light can exert pressure. That's the idea behind solar sails.
The sun has put out 3% less light per decade for the last 50 years. It may have been pushing the Earth farther out, and with less light now, it's not.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
Leap year has nothing to do with with leap seconds. Leap seconds are added due due to the slowing of the earths rotational rate. A leap year occurs when an extra day is added because the earth doesn't orbit the sun at exactly 365 days. Its 365.25... so every four years a extra day is added to keep the calender in sync. A leap second however only keeps the clock in sync.
We here at HaulmarkCards.com think about Dooms Day a lot. An awful lot. We've been trying to come up with some catchy verses and clever phrases for a new line of Dooms Day greeting/sympathy cards. We have three problems:
1. We're not sure exactly when Dooms Day will fall, so getting cards to retailers will be a logistical nightmare,2. We won't have much time afterward to spend the profits, and
3. Well, gosh! We just don't know how to "read" the public on this whole Dooms Day issue. We don't want to come off all tacky with something like, "Life was Swell, See you in Hell!" Then again "Best wishes for a Brighter Tomorrow" just doesn't give us that warm fuzzy glow that your granny has come to expect from Haulmark Cards.So we're asking you, the movers and shakers in the feel-good arena to offer up some suggestions. (In keeping with our policy of not paying for anything, these would be considered free-as-in-"free advice".)
TIAYou were 80% angel, 10% demon. The rest was hard to explain. - Over The Rhine
"Math in a song is good."-Linford
As someone pointed out earlier, the article is incorrect, and a leap second is based on the slowing of earth's rotation.
The dominant force behind the slowing is "tidal braking" from the moon. Basically, just as the moon exerts forces on the ocean, the ocean exerts forces on the moon. As a result, the moon is getting thrown gradually into higher and higher orbits because of force from the earth. The energy has to come from somewhere, and that somewhere is earth's rotational inertia.
Leap seconds were implemented as a result of branch of astronomy known as earth orientation. Basically, Earth Orientation is astronomy backwards. By looking at distant quasars constantly and monitoring atomic clocks, astronomers can see minute changes in earth's rotation. Quasars are observed because they are bright (in the radio part of the spectrum) and are far enough away that any physical motion over time would be negligible in the night sky. Correcting for leap seconds and other rotational issues like precession and nutation allows for the accurate functioning of GPS.
For more information, check out USNO's Earth orientation web site
but they know the error rate and its extremely low. They measure the particle count of cesium or some other radioactive material and the official time is an average of all atomic clocks.
Only the State obtains its revenue by coercion. - Murray Rothbard
I recently had to implement code to convert terrestrial time (TT) to martian solar day (MSD). Some interesting tidbits in that research follow.
As you might guess, the extra days in leap years help keep our calendars synchronized with our actual position about the sun (heliocentric longitude). This is called intercalation, and the general rules governing the gregorian calendar cover 400 year periods. Other methods exist which are in a sense more "accurate," but less useful for predicting future dates. Fortunately, the earth is pretty regular in its movement around the sun.
The 0 degree mark for heliocentric longitude occurs at the vernal equinox, an event that can be easily determined from earth, and has been for centuries. In the Iranian calendar, the new year begins on the day of the vernal equinox. Since this event occurs later in the day each year, eventually an extra day must be added. Such calendars are based on observation rather than rule-based model and consequently are implicitly self-calibrating.
Leap seconds, as pointed out, are an entirely different beast, and are meant to shore up the discrepency between our actual rotation and the atomic clocks we use. The current offset is 22 seconds slow officially. Oddly enough, a NASA document from 1997 uses a value of 63 seconds as the offset between TT (terrestial time) and UTC (Greenwich Mean Time). Another from 2000 shows a 32.184 second offset from TT to TIA (atomic). It doesn't exactly correlate or add up, and I'm not precisely sure why that is. Perhaps someone could enlighten me on the matter.
Curiously, our leap years follow the mathematical model while our leap seconds follow the observation method of calibration. Consequently, you can determine the correct date in the future, but not the correct second.
-Hope
Something like this was actually tested with a large group of English schoolchildren, I believe; it made a small blip on the Richter scale, but certainly nothing noticable. Fun, but as the StraightDope article says, fairly silly and pointless, as the effects can be estimated fairly easily with some physics.
--- Bwah?
Which is why soldiers march out of step over bridges, interesting java applet showing why.
A simpler explanation for those who got lost in the long words.
Each day, the sun rises and sets a little more to the north or little more to the south depending on the season. The days of the year where the sun reaches the most north or most south are solstices. When the sun crosses the middle, they're equinoxes. The official "spring equinox" is when the sun crosses the middle moving north. If you were to call that the first day of the year and beginning counting days, you will total up 365 days between equinoxes. After about four years of that though, you'll be off by one, so you'll need to add an extra day. This is called "intercalation."
One could make a rule to add an extra day every four years, but after 100 years or so, they would be foward one day too many. Skip the 100th year, and after 400 years, they'd be 1 day behind. The rule as it stands is every fourth year, except years ending in '00, plus every 400th year. Easy enough, but still not quite right.
Because the rule is not quite right, it will never be perfectly accurate. But if you follow the rule exactly, you can tell that January 1, 1601 was Monday for instance. You can also tell exactly how many days are between now and January 1, 2400 because you know which years are leap years.
The method of watching the sun and adding leap years as necessary is a great way to stay exactly on time, but really inconvenient if you need to predict exactly how every year will fall for the next 100 years or so.
Some people say so what, just live. Who cares if your birthday in 20 years is on a Tuesday. Tax collectors care... Money lenders care... Hallmark greeting cards cares... Calendar makers care... The Vatican cares... So we use the 400 year rule and call it the Gregorian Calendar. It works well enough.
As for TT, UT, UTC, TIA, ET, and a number of other time standards, well... the important thing is that we're now using very accurate clocks for counting seconds and we've determined that the earth does not spin all the way around in exactly 24 hours no matter how closely we've measured it. In fact, it had slowed down for awhile and now seems to have gotten back up to speed.
We determine the difference between the atomic clock and the earth by watching the stars go by, and after spinning, spinning, spinning, we watch the atomic clock and the sky, and if it doesn't come out just right, we assume the clocks are right and the earth is wrong. To make up the difference, we throw in an extra second once every 6 months as necessary. It hasn't been necessary since 1999 which was the crux of the article.
-Hope
Fortunately, the earth is pretty regular in its movement around the sun.
Well, according to the article, the Earth has been having trouble with regularity.
Anybody got any bran muffins?
i'd hit it so hard, if you pulled me out you'd be the king of britain [bash.org]
This could be just one more "boast" for the Bush campaign - "During my (usurped) presidency, not only did I fight terrorism, Sadam, and free markets, I also kept the world running on time!".
"The large print giveth, and the small print taketh away" -- "Step Right Up", Tom Waits
Well, everyone keeps saying the world moves faster these days. I guess they are right.
Manipulate the moderator system! Mod someone as "overrated" today.