Planets and stars are the most well-known of celestial bodies.
Stars are made up of plasma and emit light and heat. Planets, on the other hand, are composed of rock and/or gas compounds. Planets revolve around a central star called a sun.
Here is a selection of some recommended sites.
NinePlanets.org - The Nine Planets: Now officially the eight planets it gives a multi-media tour of the solar system.
Please feel free to share your favorite Planets and Stars websites (with a short description).