What forces the Earth to rotate around its axis? What about other planets?

Question

What makes each planet rotate around the axis with different time?
The Earth (or other planets) revolves around the Sun, this makes sense. But why it has to rotate around its axis?

To rotate around the axis each takes:-
Mercury: 58 days 14 hours
Venus: 243 days 5 hours
Earth: 23 hours 56 minutes (1 day)
Mars: 24 hours 37 minutes
Jupiter: 9 hours 50 minutes:
Saturn: 10 hours 14 minutes
Urenus: 17 hours 14 minutes
Neptune: 16 hours 7 minutes
*** Pluto: 6 days 9 hours

Answer 1

The planets and their moons - and the sun for that matter - all still have (more or less) the angular momentum they started with when the solar system was formed from a swirling mass of gas. The simple reason for continuing to spin is that there is virtually nothing out there to slow them down! Of course, they are gradually losing momentum but it will take a very long time for all their rotational energy to be dissipated. The solar system has been spinning away for 4 billion years so far so there is no reason to think it will stop any time soon.

Because the planets were formed from a spinning gas cloud, some of which condensed to form the rocky planets (like ours), the planets retained their momentum to end up both orbiting the sun and spinning on their own axes - the two go together really. It's highly unlikely that a planet would have kept its orbital momentum but lost all its rotational momentum.

The planets take different times to go round the sun because the nearer you are to the sun, the faster you have to go to achieve an orbit, without spiralling inwards. Kepler observed this and wrote down the equations describing the orbital periods, and Newton explained the science behind the equations, back in the 17th century.

Answer 2

Conservation of angular momentum. The Earth (and the other planets in the Solar System) formed from a rotating cloud of gas and dust. The actual rate of rotation has been affected by historical encounters since that time. Rotation speed would have increased as mass was pulled in from an accretion disk. It is suggested that the Earth gained the Moon when another planetary body crashed into the nascent Earth early in the history of the Solar System and such a collision would have affected the rotation of the Earth. Since the creation of the Earth-Moon system the rotation rate of both bodies has been affected by tidal interactions between the two. In general this has caused a slow reduction in the rotation rate of the Earth. Earthquakes and other geological activity cause redistributions of mass within the Earth which also have small effects on Earth's rotation.

Answer 3

Well, I'm no physicist, but the Earth, though basically a sphere, is not PERFECTLY round, and it's composed of all sorts of materials with differing weights, magnetism, etc.

So I think that the gravitational pull of the sun is acting in varying strength on different points of the planet as it revolves (like, say it's pulling harder on the Alps than the Atlantic ocean. If you take a beach ball and strap things of different weights around it then put it on the surface of a pool, it rotates until it can find some sort of equilibrium, which on an orbiting planet would constantly change.) I'm pretty sure that this is a huge oversimplification on my part, but like I said, I'm no physicist.

Answer 4

Earth‘s axis is slowly drifting, once it was the North pole,
drifted to Alaska, now it is over Siberia. Recent studies
suggest that the earth may tumble to it‘s side in which case
the North pole would be the present equator and vice-versa.
We will not be around to see or suffer this move, but it is
mentioned in Science and Space Alerts. Check it out.
Concerning other planets, I have no idea. Note: above
mentioned polar drift refers to Magnetic Pole which is now
far from the North Pole.

Answer 5

Since nobody really knows, let's go with a really wild idea of collisions and near-collisions with cosmic debris. Collisions normal to the Earth's surface are going to be extremely rare. Throw in the assumption that all debris orbits the sun in the same direction as the earth, which seems to be true so far. Then it is conceivably likely that more collisions augment the Earths spin than counter it.

You will already have noticed that this argument does not account for the retrograde spin of Venus

Answer 6

Our everyday experience teaches us that an object must be "pushed" by a force in order to keep it moving. Otherwise, it will slow down and eventually stop. But this intuition is absolutely wrong. If an object is moving, then a force is required *to slow it down or stop it*, not to keep it moving. (Hence, "Objects in motion tend to stay in motion. Objects at rest tend to stay at rest.") In our everyday experience, it's the force of friction that tends to stop Earth-bound objects from moving forever. But for the Earth rotating on its axis, there is no force working to counteract the rotation (except the tidal effect of the Moon, but that's working very slowly), so you don't need to have any input energy to keep it spinning.

Answer 7

I doesn't but because of the the conservation of angular momentum there tends to be come rotational movement. However, if an external force is applied - such as tidal drag - the angular momentum can be bled off. This is why the moon's axial rotation is locked to it's orbital period.

Answer 8

What determines the initial spin-rate of a planet is the amount of angular moment it collects in its formation. Later it may slow down, and this will cause its shape to change (it becomes less oblate). The slowing down is due to interaction principally with satellites.

Answer 9

Angular momentum and Conservation of momentum. If you have a couple of months where you have nothing to do,, read up on it. You will find it quite the dull subject in history, but if you want to know science,,, learn it.

Answer 10

i think its of how far the planets are from the sun if u look and the size of the planets ( earth and mars) plus weight of planets