Nicholas Copernicus and Galileo Galilei observed that the Moon revolved around the Earth and that Earth and the other planets revolved around the Sun.

Measure distances among the objects in the solar system

a planet must orbit the Sun, have a nearly spherical shape and have a mass much larger than the total mas of all other objects

•spherical-shaped object that orbits the Sun but does not have more mass than the objects in nearby orbits

millions of small, rocky objects that orbit the Sun in an asteroid belt; range in size from < 1 meter to several hundred km

made of gas, dust and ice and moves around the Sun in an oval-shaped orbit

•debris left by colliding asteroids or dispersing comets

The Tail of light emitted by a meteoroid as it enters the earth's atmosphere

Meteors that have survived the passage through the atmosphere.