Science a GoGo's Home Page Forums General Discussion Not-Quite-Science Forum EARTH'S SLOWING SPIN-RATE

I recently heard of an argument that the slowing spin-rate of earth was partly responsible for the demise of the dinosaurs - not so much a giant meteorite or the Ice Age ? as their bulk was permissible due to the slingshot-effect at/on the surface (the same force that helps whip spacecraft into orbit) and, as earth?s rotation slowed down, the giants started ?feeling? the ?beached whale? effects to the extent that they lost their fight for life? against gravity.? Hmmm? was there merit in this madness?? I thought. After all, Brachiosaurus in particular topped the ?permissible? limit for terra firma?s at 50-odd tonnes. So instead of a short, pessimistic ?NO?, I dug around and found the following:
? There are arguments both for- and against the slowing spin-rate of earth (though personally the former would seem more logical), whilst some argue that the rate fluctuates over time.
? I ?bought into? the slowing rate idea, and the consensus among this fraternity seems to be that earth is decelerating by +/- 0.001 ? 0.002 seconds per century.
? The current spin-rate induces an equatorial ?bulge? of some 27-odd miles at the equator.
? Spacecraft launched closer to the equator require about 13% less propellant.
? A day was about 6.5 hours long when earth was formed about 4.5 billion years ago.

Per my humble math the earth has gained a measly 1 hour per year (relevant) since the time of the dinosaurs about 200 million years ago, so it?s about 45 minutes gain per year (relevant) until their extinction about 65 million years ago ? hardly enough to induce drastic change, let alone extinction. Anyway, the rate of reduction was/is so slow that (here we go) evolution would have had sufficient time to work its magic, and besides, the effects (as per the ?argument?) relevant to equatorial/polar proximity vary accordingly.

And my point is? It?s interesting to have ? in the process - learnt a bit more of the effects of the gradual slow-down of earth: its effects on the landscape, climate, ocean levels and the subsequent counter-effects on, and of, Mother Nature ? things I haven?t really considered too much about this seemingly humble process that affords us, inter alia, dawn & dusk, day & night. Also: don?t go trying any new golf clubs from Pro-Shops near the equator ? your improved long-drives could be misleading. (and for those who think I?m being serious?;-)

Quote: A 15% increase in the equatorial circumference of the faster rotating young planet, relative to its present rotation, could produce approximately 3600 more miles of surface around the young planet's equatorial zone. This was a lot of surface to crunch into the ever-changing shape of the planet as its rotation gradually slowed over the ages.

For some interesting reading pop ?is earth slowing down?? into ask.com or go to http://www.creation-answers.com/slowing.htm or http://www.novan.com/earth.htm for a quick browse.

And that?s all I have to say about that.

"I know the human being and fish can coexist peacefully." --George W. Bush, Saginaw, Mich., Sept. 29, 2000

I recently heard an argument that all of the dinosaurs were purple and named Barney.

Unfortunately the Cookie Monster ran out of cookies and attacked them causing their mass extinction.

Both arguments ... the one you heard and the one I just wrote ... are of equal value.

It is considered factual by those that are supposed to know such things that the rotation of the Earth has been solwing down as a result of the Moon's drag on us.

I once used their estimate of the ffect in an effort to reverse project the data to see if I could arrive at a reasonable date when we first acquired the moon. not productive. No data on what our rotation velocity was originally, no data on our probable orbit then and no assurance the degratation was uniform. Still fun to try.
jjw

The earth never acquired the moon. The moon is part of the earth knocked out by a collision: It is us.

Hi DA:

Some people think as you recite.
That suggests that the Earth originally contained both what we now weigh in at, plus the weight of the Moon and plus whatever went flying off into space. I go for the other view. There does not appear to be amajority conclusion.
jjw

Then explain the isotopic composition of both by some other means that satisfies all known research results.

There is no need for me to try to explain something the experts still find unsettled.

I suppose you adhere to the "Big Whack" theory or whatever and I have no quarrel with that.

http://www.pbs.org/wgbh/nova/tothemoon/origins2.html

The people involved with such things give me the impression the jury is still out on the issue. You tend to be conclusionary in your approach, kinda like taking sides. That should provide a lot of comfort to pick an answer and hang on to it. It saves you from ever doubting; possibly.
You and the people that came up with the chunk of Earth script may be correct. I am unsure.
jjw

In a sense the jury is still out on all matters of science. But the isotopic evidence is in and has convinced most of us that the earth and moon are sisters.

The problem here is that Science can't agree with itself. How are non-scientists supposed to know the truth. After all, the truth is out there, it just takes a bit of finding and a concerted effort to come up with truthful theories based on scientific logic, not based on someone trying to further their own career!

I have just registered. I am that anonymous person of the previous entry.

Science should be about 'the scientific truth'. Not someone's idea of 'The Truth'. There is only one 'Truth'. The fact that some of you are arguing about it means that the 'Truth' has yet to be found. Keep doing the research. You'll get there in the end.

Cheers
MarkS

All truth in Science is provisional. I know that doesn't fit your ontology of "truth", but how can anyone know, by themselves, that any perception is true? Science is a collective enterprise, and like all things that masses of humans do together there will be disagreements.

Back to Topic:

Earth's current spin reduces the felt gravitational force at the equator by 0.3%. According to the Big Smash theory the Earth's original spin-period was about 1/4 of its present day level. As centripetal acceleration is a = r.w^2, that means the reduction was ~16 times more, ~4.8%, but the Earth also bulged more because of the gravity reduction. In total the reduction was probably ~5%, which really isn't enough for a noticeable effect on dinosaurs or any other large animal.

But it's all irrelevant as we're learning that dinosaurs were somewhat lighter than first thought because they had very pneumaticised bones - their bodies were full of air-sacs just like birds. Thus their architecture was quite different to the large mammals of the past.

when I read this I wondered if you could use the mass of the earth and the mass of the moon as a starting point.

using the current angular velocity of the moon should give its current radius from the earth.

and tell how far out the moon slips in its orbit each year due to the centripetal force supplied by gravitational forces.

from there you should be able determine the angular velocity of previous years by bringing the moon in closer in in each calculation.

the moons angular velocity is speeding up , or it is getting heavier otherwise it would not be leaving us.

from here you should be able to determine the moons capturability
by the earths gravity and at which point in time the moon was captured.

I personaly dont think the moon was captured , I think either the earth jetisoned the moon durring a past ice age when the waters of the earth were mostly at the poles and the reason for this would be the continual angular acceleration of the earth as the waters moved in closer to the center of rotation of the earth by forming ice at the poles.

or the moon was a result from a asteroid hitting in china
and exiting just west of central america.

but either way its interesting to think about these things.

[quote=Mike Kremer]

It certainly is Paul.
I am afraid I dont subscribe to the current theory that the Moon was formed as result of a large body slamming into the Earth in the far distant past. For two main reasons.
A\No magnetic field on the Moon. (Therefore unlikely that our iron core was transfered to the Moon, from Earth)
B\Such a hard slam, would most probably produced Moonlets, or small bodies, if still around, where are they now?
I prefer to believe that the early Earth had two large bulges on the equator, one was Pangea or Gwondanaland, a single large land mass from whence all the present Continents separated and formed, (still going on today)
While the other, on the other side of the Earth, was an even larger mass than Pangea.
This was gradually thrown into the position the Moon occupies now, by the centrifugal force, of the faster spinning Earth, of that time.
Moon might have centrifuged out the larger land mass (toffee like) from where the huge Pacific deep basin, exists now. Where indeed the crust is a lot thinner and deeper than anywhere else on Earth (ever wonder why?)
Being centrfuged out, toffee like, could well account for the fact as to why the Moon keeps the same face to us at all times. It would help explain why we kept our iron core, while the Moon got none?

Remember our present continents are still drifting to fill up the Pacific deep area, where our Moon might have come out from.!

I find it beyond comprehension that the theoretical 'wack' the Earth got, would not upset the spin of the earth.
Its still spinning in just the same orientation as the rest of the Planets. (apart from one retrograde one)

Don't forget that the rocks on the Moon have been found to be the same composition as those here on Earth.
(Not so those on Mars, they can hunt for Martian rocks here on Earth precisely because they are different).

It might have even accounted for the gradual accretion of water here on Earth that occurred over a long period of time, (since the Moon is not large enough to keep its water, it could well have had a vapour cloud around it,
which bled off Earthwise, and Mars-wise over the millennia?.

No, I am afraid I am not one who believes that the Moon was formed by the glancing blow of a body that struck Earth, millennia ago.
I just think that the Earth, and Mars would still have had some sort of rings around them, like Saturn? Formed by the debris of collision.

Mike



Your right , and even if the debri were there and they were pulled into the earth by gravity , there would be a distinct band of impact craters on the earth !! and the moon , as I understand there is no such band of impact craters either here or on the moon.

Your thoughts on the moons water vapor makes so much sence to me , a blob of magma oozing out of the earth due to the inability of centripetal force to push hard enought inwards to allow it to remain a part of the earth , or centrifugal force , or as is deemed necessary to comply with usual mathmetical standards , the angular velocity of the earth was too great and the magma was spewed out of the earth and formed our moon.

man , the trouble you go through to accomodate the nick - pickers.

when I used to write about the CFPFM and -- centrifugal force --

it did not exist , it was a psuedo force , and centripetal force was the only force in rotation , there were no people on this forum that believed that this type of thing occured.

you remember the CFPFM that could have put an end to all of the current climate problems , so I claim...

the one that the D.O.E. would not fund...mainly because of the $0.48 in taxes they get for every gallon of gasoline sold here in the U.S.

anyway , now people have begun to use the word here in this forum.

fact is it is a psuedo force , but I have adapted to use other more commonly used words to describe the effect.

anyway , there would have been a great amount of water that would have been spewed out along with the magma , and this water would have moved towards the surface of the moon and form vapor.

this would explain the reason the moon always faces the earth with the same side , the heavier magma is closest to the earth
just like the heavier magma is closest to the earths core here on the earth , due to gravity.

and it is the gravity of the earth and the gravity of the one side of the moon that holds the moon in its position.

the moon would have cooled rapidly , especially the surface and
would have cooled from the outside in.

since the moons heavier matter is located closer to its surface
and that matter was locked in the moons crust that formed just after the moons formation , may be the reason the moon has no core , and why it is a solid body.

which gives evidence of its viability as a captured body would be rotating.

a body formed from gasses would be rotating , even a body formed from a massive number of collisions would be rotating , and not always presenting the same side to the earth.

the fasting spining rate of earth ,....
may be 25-26 hours a day in the dinosuar age.

faster make things heavier.
the land seperated...
i just imagine
sorry for my english.

kob

25-26 hours would be a slower spin rate.

we are now in a 24 hour spin rate.

a faster spin rate would give things more angular velocity
and in doing so things would have more centrifugal force
but the gravitational force would remain the same.

...note...
centrifugal force is a term that is used / I used to describe
angular velocity , and is not itself a real force.
but angular velocity can cause a object in rotation to move
away from the center of rotation at a 90 degree angle from the center.
..... note is to avoid nit picker replies .........

I imagine that the earth was spinning pretty fast when the moon was ejected and when the earth lost the mass that formed the moon the earth also lost the kinetic energy that was in the mass.

and as the void was replaced any slower spinning mass would require an extra amount of force to accelerate the slower spinning mass that filled in the void.

that extra force came from the existing kinetic energy that the earth had remaining after the moons mass was ejected.

thereby greatly reducing the earths spin.