David Aul, age 15, of Conyers, Georgia, for his question:

Do all the planets revolve in the same direction?

The nine planets and also most other members of the Solar System are traveling around in the same direction. The circling system is somewhat like a saucer and to evaluate its motions we should try to visualize it from outside. We may consider the top side of the saucer to be our north direction    that is towards the earth's north polar axis. The bottom side then would be toward our South Pole. These markers have little or nothing to do with the vast reaches of the universe, but we need basic markers of some sort from which to figure the direction of motions.

Using our earthly north direction, let's zoom far out into space toward Polaris. From this imaginary point we can look down on the top of the Solar System. We can watch the nine planets revolving around the sun at different speeds, but all in the same direction. They revolve as the earth does, toward the east in a counterclockwise direction. The sun also rotates around its axis in the same direction and when viewed from the right position, so do all the planets. Most of the moons also orbit their planets in the same direction, though a few lunar oddballs are known to orbit backwards, toward our west direction.