The planets are kept in their orbits around the Sun by the force of gravity. Gravity is a force that attracts objects to each other. The more massive an object is, the greater its gravitational pull. The Sun is much more massive than any of the planets, so its gravitational pull keeps the planets in orbit around it.

The planets orbit the Sun in elliptical paths. This means that their orbits are not perfectly circular. The planets' orbits are also tilted with respect to the Sun's equator. This means that the planets' axes of rotation are not perfectly aligned with the Sun's axis of rotation.

The planets' orbits are constantly changing. This is due to the gravitational pull of the other planets and the Sun. The planets' orbits also change due to the effects of the Sun's magnetic field.

Despite these changes, the planets remain in their orbits around the Sun. This is because the force of gravity is very strong. The planets are very small compared to the Sun, so the Sun's gravitational pull is much stronger than the gravitational pull of the planets on each other.

The planets' orbits are a complex system, but they are governed by the laws of physics. The force of gravity is what keeps the planets in their orbits around the Sun.