How do planets rotate

As an interstellar cloud collapses, it fragments into smaller pieces, each collapsing independently and each carrying part of the original angular momentum. The rotating clouds flatten into protostellar disks, out of which individual stars and their planets form. By a mechanism not fully understood, but believed to be associated with the strong magnetic fields associated with a young star, most of the angular momentum is transferred into the remnant accretion disk. Planets form from material in this disk, through accretion of smaller particles.

In our solar system, the giant gas planets Jupiter, Saturn, Uranus, and Neptune spin more rapidly on their axes than the inner planets do and possess most of the system's angular momentum. The sun itself rotates slowly, only once a month. The planets all revolve around the sun in the same direction and in virtually the same plane. In addition, they all rotate in the same general direction, with the exceptions of Venus and Uranus. From the surface of a non-spinning planet, its sun would appear to move across the sky, but the other stars would be stationary.

However, this would mean that Venus would still be spinning a tiny bit, with a period of something like million years, because our solar system orbits the centre of the Milky Way in that time. Also, some rogue planets that have been knocked out of their solar systems and wander across the cosmos might have lost their spin due to chance interactions and collisions with other objects. Planets originate as dust particles that are attracted to each other mainly by static electricity. Once all those accumulated particles build up enough mass, then gravity will attract other masses.

As particles hit the developing planetoid, they are likely to hit offset to the centre of gravity. Each particle, pebble, rock asteroid and comet that strikes provides more angular momentum as they hit at an angle and contribute to the growing planet. It is unlikely that all contributing debris would hit the planetoid directly on the centre of gravity and therefore, it is likely that all planets will rotate. Random Question. Why do airplanes take longer to fly West than East?

Most Recent. Is speed of light the same everywhere? Beginner How does Venus have sulphuric acid in it's clouds? Intermediate Why is the sun red? Beginner But seriously: what was there before the Big Bang? Beginner How far can photons move freely in the early universe Advanced How likely is it that the Solar System has had or will have a close encounter with another star?

Intermediate How do we know what we observe is x light years away? Editor's Pick. What is the universe expanding into? Intermediate What do I need to do to become an astronomer? Beginner What's the difference between astronomy and astrology? Beginner Why is looking out into space the same as looking back in time? Beginner Can we find the place where the Big Bang happened? Most Popular. How long could life on Earth survive if the Sun stopped shining? Beginner Are there telescopes that can see the flag and lunar rover on the Moon?

Beginner Why are Saturn's rings flat? Intermediate What is the difference between a "star" and a "sun"? Beginner How can a star burn with no oxygen? US state, Canadian province, or country. Tonight's Sky — Select location. Tonight's Sky — Enter coordinates.

UTC Offset:. Picture of the Day Image Galleries. Watch : Mining the Moon for rocket fuel. Queen guitarist Brian May and David Eicher launch new astronomy book. Last chance to join our Costa Rica Star Party! Learn about the Moon in a great new book New book chronicles the space program. Dave's Universe Year of Pluto. Groups Why Join? Astronomy Day.