# Geek Trivia: In what year is the current Gregorian leap year system expected to 'fail?'

A recurring margin of error is building in the leap year system that suggests it will fail -- as in, the vernal equinox will be more than a day removed from March 21 -- at a particular date in the future.

One of the more intriguing aspects of astronomy is that it teaches us a year is not actually a year. More specifically, a calendar year (365 days) is not equivalent to an astronomical year (roughly 365.25 days), which is why we must (triple word score alert) intercalate an additional day into the calendar every four years to make up the difference. Thus, for those of us who observe the modern Gregorian calendar, the quadrennial appearance of February 29 will go down in just six days.

Except that, strictly speaking, February 29 isn't a quadrennial event. A Gregorian leap year is observed every four years except in century years. Thus, the year 1900 was not a leap year. However, every fourth century year is a leap year, so the year 2000 included a February 29. Why all the conditional intercalation? Because an astronomical year isn't precisely 365.25 days -- it's closer to 365.2425 days, or 365 days, 5 hours, 49 minutes, and 12 seconds. The intercalated adjustments are made to ensure that the vernal equinox stays on or about March 21 of every year.

Yet for all these allowances, the modern Gregorian calendar is still inaccurate, as the astronomical year isn't precisely 365.2425 days long. A recurring margin of error is building in the leap year system that suggests it will fail -- as in, the vernal equinox will be more than a day removed from March 21 -- at a particular date in the future.

IN WHAT YEAR WILL THE GREGORIAN LEAP YEAR SYSTEM "FAIL?"

Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

premdas67

Humans invented this calender thing and now behave like the whole cosmos runs as per the thing. The mind boggles.

crcgraphix

For instance, one type of stellar science that is credible and vast is Vedic Astrology, and it also overlaps with astronomical science as well. In depth, the Vedic form of Astrology is actually derived from both Arabic and Indian origins. I delved into this some more and found that if you refer to these symbols on astronomy, a stitch in time and energy is created. It is kind-of a cross between the major and minor houses of the stellar realm and the Arabic Parts. Kavhli and Balic astronmony-astrology which is highly an Indian culture, is also very precise and accurate. It is very much inter-twined with astronomy as well. So, in my belief, I think that if we use another form of metaphysical study, we and the experts can derive a form of new inductive reasoning for as to how the so called leap year can be accentuated through tinkering around with the Gregorian Calendar. We all know that time is inconceivable depending on how it is perceived, but that doesn't mean we cannot manipulate it. So, thus, this long-standing form of science still remains strong. We go by the Julian Calendar, however many pagans and occultists use the Gregorian Calendar sometimes. It is likely that we have become thought-provoked here, and know we will overlook the meanings that are behind our society's choice of a calendar. Hopefully, they are already working on this, but in more importance, we can change the ways things unfold with our own free will, whether it be a calendar, an assignment, or a long-planned event; we have the choice to determine the most possible outcomes for ourselves.

Dukhalion

Because since all our calendars have an arbitrary beginning, we can change them anytime we want to, just like pope Greg did in medieval times. Besides, this isn't 2012 to all people in the world. The muslims have 1433, buddhists have 2556, You can check the rest here: http://en.wikipedia.org/wiki/Template:Year_in_other_calendars So, should we call next year Wikiyear 1, and reset all inconsistencies?

AnsuGisalas

Someone had the audacity to claim that feb 29 is not in actual fact the leap day. The outrageous claim was that the actual leap day is inserted a few days (4?) before the 29th, causing the following days to shift one place upwards. I keep telling myself that that makes NO sense, but it keeps haunting me, anyway. Has anyone else in the halls of geek learning heard of such a claim? And, if so, can you tell me: WTH?

AnsuGisalas

will have found our calendars, and they'll look at the leap years and the antileap years and the antiantileap years... and they'll worry. They'll worry the world will come to an end on 3/21/8000 :p :^0

If any of you plan to be around in the year 8K, good for you! I'll be happy to get through the mayhem of December 2012, thank you!

gherardini

leap years are skipped in century years that end in 00 except when they can be evenly divided by 400. so while 1900 didn't have one, 2000 did.

ejkolkman

If breaking tides and earthquakes are causing the Earth's rotation to slow, what happens if it stops completely, and will a faulty calendar system even matter anymore?

bikingbill

How many hundred years ago was the Gregorian calendar worked out? And how primitive were the instruments available? The long-dead astronomers who did the work must have been remarkable thinkers.

jonniebgood

but as long as Saturdays and Sundays continue to follow Fridays, I'll remain a happy camper. In the meantime, I'll make a note on my calender to check up on this in 5988 years from now, just to see how accurate the current estimate is.

acees

Is earth's appearance from moon same as that of moon from earth, i.e. whether there is New earth day and Full earth day from moon as happens for moon from earth, i.e. New moon day and Full moon day?

AnsuGisalas

If you have nothing nice to say, save it until you're smarting for a fight.

AnsuGisalas

But it's still not moot, the calendar year can't very well be the same as the astronomic year, and if it isn't then we need to add and subtract... and if we only have a threefold iteration (quadrannual (-), centennial (-) and quattrocentennial (+)), then we get a fail in 8000... moving new-years won't help since it depends on the time of the equinox.

NickNielsen

It makes NO sense whatsover. I think somebody was having you on...

AnsuGisalas

Century years that end in 00? Don't they all? Anyway, the best description is the one that keeps one variable only: A leap year is a Gregorian calendar year that is evenly divisible by 4, unless it is evenly divisible by 100, but with the addition of years evenly divisible by 400.

LedLincoln

...so our nice calendar is remarkably precise. It won't exactly "fail" for quite a while to come, but some digital bugs similar to Y2K might crop up on the even centuries, i.e. 2100, 2200, 2300, and 2400. I'll be watching.

JJMach

Mostly, I'd say no, due to a matter of time. At the current rates of deceleration, it will take several billion years to stop, but now you need to account for other factors (the moon is drifting away, reducing its slowing effect, etc. etc.), which may result in the Earth being swallowed by the Sun long before, and definitely long before humanity will care or have more than sufficient technology to "fix" the planet so that it keeps perfect atomic time. If it was going to stop while we are still around, it also depends on how it stops. If we were to be tidally locked with the sun (as the Moon is with Earth), then one side would always face sunward and become an inhospitable, melting desert. The far side would become a frozen wasteland. There might be a habitable band from pole to pole, and if we were real lucky, it would contain our major land masses (and not run through the Pacific and Atlantic). If we were to stop rotating completely (relative to the solar system), a year would be a day and the seasons would go from searing hot to unbearably cold. Only small regions near the poles would remain somewhat livable. Either way, we would have bigger fish to fry than to argue leap-days. If the Earth's rotation were to stop suddenly, then all bets are off. The mega-tsunami, earthquakes, volcanism--let's be honest: tectonic shattering--will exterminate all life. So there, *pbltpblt* :P (A childish way of saying QED if there ever was one.)

VictorGutzler

According to Witold Fraczek (link to his discussion at http://www.esri.com/news/arcuser/0610/nospin.html), a day would last a whole year and the current centrifugal force causing the oceans to pond along the equator would no longer be in effect, so there would be land ranging all around the earth's equator separating two oceans at the poles. No more Great Lakes or Lake Bakal, no more Mediterranean beaches. And weather would be drastically effected, probably producing huge desert regions that dwarf the current Sahara and Gobi.

Dknopp

The gregorian calendar - and others, Julian, Hebrew, Chinese, Islamic, and the calendars that are no longer followed like the Mayan calendar are all based on lunar cycles, the rotation of earth and earths journey around the sun. These were worked out thousands of years ago ( and probably much longer ) to pretty exacting degree. The calendars that we use now were all based on those ancient sitings and are just basically mathematical organizing of the data. We tend to think that those ancients were not as intelligent as we are, but in reality they had the same deductive brain power, we just have the luxury of knowledge that has been added and compounded throughout the millenia. I have a fantasy of being back in those times just sitting on a knoll on a warm summer night on a hilly plain somewhere looking at the stars ( with no light pollution )and trying to figure out what is what.....and then a sabertooth tiger attacks, or I die from some easily fixed festering infection - something to be said for that compounded knowledge.

rpb_

Although, because of the orientations of the earth and moon at new/full moons, the new/full earths occur at opposite times (i.e. at full moon from the earth it would be "new earth" from the moon). Also, the earth would appear much larger in the moon's sky, than the moon does from earth, of course.

AnsuGisalas

From Wikipedia: [b]The leap day was introduced as part of the Julian reform. The day following the Terminalia (February 23) was doubled, forming the "bis sextum"literally 'double sixth', since February 24 was 'the sixth day before the Kalends of March' using Roman inclusive counting (March 1 was the 'first day'). Although exceptions exist, the first day of the bis sextum (February 24) was usually regarded as the intercalated or "bissextile" day since the third century.[1] February 29 came to be regarded as the leap day when the Roman system of numbering days was replaced by sequential numbering in the late Middle Ages.[/b] Grraaagh, but what a piece of geek trivia, eh? I look forward to saying at parties that "He was born on a leap day, Feb 24 1896..." just to see the WTH faces :p

Michael Jay

By then the sun will be working on its red giant stage, I do not think we have time for the earth to slow to a stop before the sun fails.

JJMach

Fraczek puts a lot of words behind his idea...and completely neglects that the magma under the crust is a fluid too. The same centrifugal force that causes the oceans to bulge at the equator also causes the Earth to bulge similarly. If the planet were to stop spinning (gently enough to not destroy the planet), it seems likely that the earth and sea would adjust in the same way so as to end up with an Earth that looks the same, if a bit more round.

Arcturus909

The Earth would also eclipse the sun every single month, if you were living on the Moon.

Michael Jay

people who did not believe that the earth was the center of everything, were imprisoned, or worse. Just another case of belief overriding science, Galileo got off easy with just house arrest for life, I guess they liked him and knew he was right, but still refused to accept it due to their beliefs.

AnsuGisalas

I guess I lost track of the different kinds of rotation. Ultimately though, without absolute space, rotation is a relative thing. We can easily posit that the earth is standing perfectly still, in an imaginary universal origo, and everything else just hurtles about in a very haphazard way :^0

Michael Jay

not the orbit, the orbit is stable, it is only the rotation on our axis that is slowing.

AnsuGisalas

If it "slows down" it will "drop" into a lower orbit - remember that orbiting is actually "falling into the sun, but missing by a constant amount". Less missing means lower orbit. The Earth won't experience serious "braking" until its orbit reaches the denser parts of the sun... which would make the whole thing rather academic from my perspective.

djed

what happens if you're on the moon and the sun is eclipsed by the earth. I don't think that's what you're talking about.

NickNielsen

It happens only once a month (well, every 28 point something days, anyway) ;)

djed

if you call nighttime "shadowtime." The dictionary says a shadow is a dark area cast on the ground or some surface by a body intercepting the light. But that happens more than once a month.

NickNielsen

is the side away from the sun, that's pretty much what happens, eh?

djed

The moon's shadow falls on the moon?

Michael Jay

a lunar eclipse viewed from the earth is a solar eclipse viewed from the moon, on the moon you would get about 2 per earth year. But given that the earth has an atmosphere, the edge colors would be very cool.