Anyway, the basic reason why the planets revolve around, or orbit, the Sun, is that the gravity of the Sun keeps them in their orbits. Just as the Moon orbits the Earth because of the pull of Earth's gravity, the Earth orbits the Sun because of the pull of the Sun's gravity.

Why don t the planets fall into the Sun?

Paradoxically, it is the Sun's gravity that keeps the planets in orbit around it, just as the Earth's gravity keeps the Moon and satellites in orbit around it. The reason they do not just fall into the Sun is that they are traveling fast enough to continually "miss" it.

Why do planets rotate?

Round and round the planets spin. This is simply the result of the initial rotation of the cloud of gas and dust that condensed to form the Sun and planets. As gravity condensed this cloud, conservation of angular momentum increased the rotational speed and flattened the cloud out into a disk.