Solar System

Earth has seasons because its axis doesn't stand up straight. So instead of rotating with its axis straight up and down, it leans over a bit; thus causing seasons.

In the Solar System a planet is a celestial body that is in orbit around the Sun, has sufficient mass so that it assumes a nearly round shape, and has "cleared the neighbourhood" around its orbit.

An asteroid is an irregularly shaped rock that orbits the Sun, mostly occurring in a band asteroid belt between the orbits of Mars and Jupiter. Asteroids range in sizes, but tend to be smaller.