For a long, long time, people thought that the Sun and all of the other planets revolved around the Earth. This was called the geocentric, or Earth-centered, model of the solar system. Of course, now we know that the Sun is the center of the solar system, not the Earth - the solar system is actually heliocentric, or Sun-centered.
But the geocentric and heliocentric models had something in common - astronomers used orreries to study them! An orrery is a mechanical model of the motion of the planets in our solar system. Try making your own orrery by downloading the printable here!