Earth's rotation?

Question

Why does the Earth spin on its axisis?, what makes it do this rotational movement? which causes night and day to occure.

And Mike G's answer is ridiculous

Answer 1

The most widely accepted view of how stars, planets, solar systems and galaxies are formed is through clouds of dust and gas coming together under the influence of gravity. Assuming this is an accurate theory, it would be amazing if all that mass came together from different directions, and the net angular momentum of the whole was zero. Hence,just about everything spins, and for the same reason, you will note that the planets (nearly) all spin in the same plane as the plane in which they orbit the sun, and all orbit in the same direction. Hope this helps.

Answer 2

Here's how I view it:

Billions of years ago, the earth was likely a "cloud" of gases and space debris that happened to be close enough so that over time, the gravitational pull of the gases and other debris on each other caused them to move closer together and eventually form the earth.

Now, the particles in the cloud likely had a small amount of motion to them besides the motion toward the center of the cloud caused by the force of gravity (perhaps because they were the remnants of star that was thrown off or collided). So the cloud was probably spinning slightly.

As the cloud (probably millions of miles in diameter) came together to become a planet (less than 8000 miles in diameter), the speed of rotation increased dramatically because of conservation of rotational momentum. Just like the ice skater who pulls his or her arms closer together increases rotational speed!

Rotational (angular) momentum is always conserved, so the earth continues to rotate unless there is another force that stops it from rotating or slows it down.

Answer 3

Earth is spinning on momentum left over from it's creation. Just like a top keeps spinning for quite a while after you let go, so does the Earth. The top eventually slows down due to friction, but there is practically no friction in space. The Earth's spin IS slowing very slightly, but it would take millions of years to slow to a stop.

Answer 4

Jimbo right, Alexis not. But I don't really know the full answer.

I'm assuming it's just the law of conservation of angular momentum (Newton for spinning things - more confusing, but the same). This particular bit of residue of the big bang ended up stuck with some spin, and it's still got it. Different objects in space spin different amounts, so have different lengths of days.

The moon does not spin - the same side of it is always pointing towards earth. That's because it solidified in the influence of earth's gravitational field, causing it to end up with more of its mass concentrated to our side. Like Mr Wobbly Man - even if you knock him, he always pops up the same, cos he has a heavy ****.

Answer 5

Its just how things are right now, no one knows much past that. We could keep going on to say why did this ball of stuff even turn into a solar system, why did this ball of stuff come out of a "big bang," and what the hell is the big bang? Start with nothing? What's that, where is it? And an explosion happens; nothing to something? This is just how things are this time

Answer 6

Since the sun pulls objects towards it, because its a greater mass, the earth got caught in its gravitational pull while spinning. Thats why we have days/nights.

Answer 7

it is spinning because if it was not.. one side would melt from the heat of the sun!!! and the other side would be frozen... and too cold to live on.

ok... theory... of how the solar system was formed... and.... conservation of momentum..

Imagine the sun... got it? no earth orbiting it.. just a bunch of debris left over from formation of sun... debris at about the orbital distance of the earth from the sun...

now.. take one of the larger pieces of debris... and in space it's gravitational attraction on other objects around it.. would cause them to move toward it.. and collide with it.. making a larger object... the impact would generate heat (like hitting something with a hammer repeatedly).. ok.. heat would eventually make a molten ball.. so we would have a sphere of molten mass that debris was falling into as the newly forming planet travels around the sun...

ok.. now... an experiment... take a weight and tie it to a string and swing it around you... now.. at some point.. measure it's speed and try to keep it constant... once you have it constant... let out more string so it is about 3 feet farther out from you.. did it speed up? or slow down? (by conservation of momentum .. it should have slowed down in it's "orbit" around you)

this is like debris being attracted to the new "earth" from orbit nearer to the sun.. it is slowing down

now... pull the string in.. so the weight is closer to you than it was at the outter part.. by about 6 feet.. is it now moving slower than original or faster?... ... this is like debris being drawn in from outside the "earth's" orbit

so.. you have faster debris on outside orbit.. slower on inside orbit... difference causes a rotation to form.

Answer 8

What amazes me is not that the earth spins but that one rotation takes exactly one day!

Answer 9

dunno if you just messin about mike g, but its no coincidence. When people invented measurable time periods, one day was the time which it took for the earth to complete one revolution. It wasnt a case of 'hmmm ive just invented one day. isn't it weird that its exactly the same amout of time as the rotation of the Earth?!'

if you were foolin around, sorry to have patronised you...!

Answer 10

Take a scan at these:-

http://www.reference.com/search?db=web&q=Earth%27s+rotation