What makes the earth spin at a constant rate of speed?

Answer 1

Stars and planets form as a result of the gravitational collapse of accreting material. Any net translational motion of that initial material is accelerated as its radius of rotation decreases. This is due to the same conservation of angular momentum principle that makes skaters and divers spin more rapidly when they bring their arms closer to their bodies. In its extreme, this effect can make collapsed neutron starts spin many times each second, creating the regular beat of pulsars as observed from Earth.

Once an initial spin was established for the Earth, the same conservation principle says that its angular momentum will continue unless it can be transferred to another object. With no significant frictional forces to allow that to happen, the Earth can continue to spin indefinitely without any further prodding. (More on that later.)

It is incorrect to say that the Moon does not spin. It rotates on its axis in synch with its revolution around the Earth, keeping the same face always pointed toward us. If it did not rotate at all, we would see all of its surface over the course of one month's orbit. This condition was created by tidal forces between the Earth and Moon, gradually slowing its initial rotation until the current more stable situation evolved. This same 'tidal lock' condition has been observed for satellite closely orbiting other planets. Because of its elliptical orbit, a slight 'wobble' allows us to actually see slightly more than half of the Moon's surface over the course of a month.

Tidal forces, by the way, continue to affect the Earth/Moon system. They exert enough frictional force on the Earth so that some of its angular momentum IS being transferred slowly to the Moon. The net effect of that is to gradually slow down Earth's rotation and lengthen the day. Where is that energy and momentum going? The moon is gradually receding from the Earth. Both of these effects are small. The Moon is receding at a rate of less than 2 inches per year and the day is getting longer by one second every 67,000 years or so.

Answer 2

The Earth keeps spinning at a fairly constant speed, due to the conservation of angular momentum... basically like a top - it would keep spinning, if it were not for friction.

Now remember I said fairly constant.. the Earth is slowing down.. This is actually due to the Moon's pull. As you know, the Moon causes the Earth's tides. This actually exerts a pull to slow the rotation of the earth.

I don't remember the details, but the Earth used to be spinning significantly faster (mathematicians worked out the speed of deceleration, and worked backwards for the old rotational speed of Earth)... I think the days were like eight hours long. I could be wrong about that number, I learned that fact a few weeks ago, and do not recall much.

Answer 3

Newton said "an object in motion tends to stay in motion." There is nothing to stop the earth from spinning, and to do so would require a tremendious amount of energy.

As for why it is spinning, it's leftoever momentum from the formation of the earth, which was created from a spinning cloud of gas and dust.

Answer 4

Inertia. Rotational inertia, that is. Also called conservation of angular momentum.

Things that make the rate change:
-- winds (exchange of angular momentum with the atmosphere)
-- tides (exchange of angular momentum with moon and sun).
-- ocean loading (force of ocean currents on the sea bed)
-- core dynamics (earth's core spins faster or slower)
-- crustal motion (earthquakes, mostly)

These all add up to about 12 milliseconds per day, over 272 years of observations.

Answer 5

It does NOT spin at a constant rate. It is slooooowing doooown.

Answer 6

God is who.

Answer 7

god