imaginary line
2006-09-18 00:57:00 · 12 answers · asked by sawawerewolf 1 in Science & Mathematics ➔ Astronomy & Space
Because if it didn't spin, it wouldn't keep orbiting the sun. Some experts' opinions: http://www.google.com/search?hl=en&lr=&q=earth+spin+on+axis+why
2006-09-18 01:05:15 · answer #1 · answered by alchemist_n_tx 6 · 0⤊ 1⤋
The answers given here are so complicated. Here's an easy one to understand. The answer is it doesn't necessarily have to. It's just that it's been spinning since the beginning and there has been nothing to stop it's spin.
And why did it spin in the 1st place? Well, that's how a planet is formed. There was a cloud of dust. At some point in the cloud where there is the most mass, gravity caused everything to swirl towards the center. Thus, the spin started to collect more material to form the planet. In other words, if there was no spin, earth wouldn't have formed. It's just like when you flush the toilet, everything goes into the hole but it goes into the hole in a circle.
2006-09-18 12:45:08 · answer #2 · answered by mmmodem123 3 · 0⤊ 0⤋
The kinetic state of an object can be described by it's velocity, it's rotational axis, and it's speed and direction of rotation. Those parameters will be constant if it's not subject to any force or torque from outside.
In fact, the torque from the tidal forces makes Earth's rotational axis change a little bit. You can notice this when looking at very old star maps. When the sun is, according to the Vedeic callendar, in Leo, it may actually be in Virgo because the axis of Earth's rotation has changed since the anciant Indian starmaps were drawn. That's why (or at least one of the reasons why) the starmaps used by astrologists are different from the scientific ones.
2006-09-18 08:10:50 · answer #3 · answered by helene_thygesen 4 · 0⤊ 0⤋
When you spin a top "around its axis" each particle making up the top has its own circular path and each particle possesses energy of inertia (like flywheel energy). The top would spin forever except for air friction and friction at its contact point. Of course there is virtually no air friction or contact friction to slow the earth. It would require an external source of energy to force all the particles of the earth to change their paths (new axis?) and that would require collision with another planet or a perhaps a huge comet. If you hold a spinning bicycle wheel by its axle you can feel the resistance to changing its imaginary line of rotation; you must add force to change it.
2006-09-18 08:52:49 · answer #4 · answered by Kes 7 · 0⤊ 0⤋
It doesn't have to move at all. Considering it does that is why it is called the axis. It is a relative term used. It spins on the the axis because there is no force stopping it. The Earth is a giant gyroscope.
Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
2006-09-18 08:24:11 · answer #5 · answered by ? 3 · 0⤊ 0⤋
The Earth's rotation is due to the fact that when the solar system was forming it had a spin which started the planets rotating around the sun and then around themselves. This rotation is decreasing as time passes, just as Moon is no longer rotating around itself. Eventually, earth will also stop rotating around itself.
2006-09-18 08:10:11 · answer #6 · answered by amirT 3 · 0⤊ 0⤋
It began spinning as a vortex in the nebulous dust cloud around the Sun when it was a protostar.
There hasn't been anything to cause that spin to stop.
2006-09-18 08:07:26 · answer #7 · answered by Red P 4 · 0⤊ 1⤋
earth does not have to spin, but if it didn't, we have the sun lighting parts of earth once every year. so the lighted parts will burn and the dark parts will freeze over.
2006-09-18 08:08:49 · answer #8 · answered by Anonymous · 1⤊ 0⤋
Spin a ball some time and watch it. Then imagine it in a vacume of space.
2006-09-18 07:59:43 · answer #9 · answered by scoop405106 1 · 0⤊ 1⤋
it's a break dance sweet heart
2006-09-18 08:06:17 · answer #10 · answered by Anonymous · 0⤊ 1⤋