Do all planets spin in the same direction

A.� Yes, apart from one: Venus spins on its axis in a clockwise direction, the opposite direction to all of our solar system's planets

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Q.� So the Sun rises in the west rather than the east on Venus

A.� Yes, but since a day lasts rather a long time on Venus, 243 Earth days to be exact, this doesn't happen very often.

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Q.� Why does Venus spin in the opposite way to all the other planets

A.� Scientists believe that Venus started off spinning in the same direction as all the other planets but that something happened to send it into reverse.

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Originally it was suggested that Venus had possibly been turned upside down, which is why it now spins in an apparently retrograde or backward direction. At first scientists suggested that something pretty big must have slammed into it, causing it to flip over.

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Q.� And the next theory

A.� Later scientists realised that Venus could have flipped over due to much more subtle forces than a huge collision. They suggested that high-pressure bulges in the planets atmosphere, caused by the suns heat, could have eventually produced enough of a tilting force to flip Venus over.

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Q.� Sounds good, what happened

A.� In order for this to be possible Venus would have had to be virtually rotating on its side to begin with. But the high-pressure bulges idea did pave the wave to the latest theories.

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Q.� What are the latest theories

A.� That the bulges acted in combination with the gravitational pull of other planets, especially Earth, which passes very close to Venus, creating an unpredictable tug of war of forces which could have pulled Venus over.

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This would have been made even easier if Venus had a relatively slow spin to start with which would have been easier to upset.

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Alternatively some scientists now believe that Venus hasn't flipped over but that it was rotating so slowly to start with that the combined forces of the bulges and other planet's gravitational pull were sufficient to slow Venus to a standstill and send it into an anticlockwise spin.

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Q.� What makes Venus so different

A.� Of all the planets Venus was the most likeliest to flip over, it has a heavier atmosphere, almost 100 times heavier than Earth's, and it's close to the unusual influences of the sun.

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by Lisa Cardy