Amateur astronomy, a subset of astronomy, is a hobby whose participants enjoy studying celestial objects. It is usually associated with viewing the night sky when most celestial objects and events are visible, but sometimes amateur astronomers also operate during the day for events such as sunspots and solar eclipses. Amateur astronomers often look at the sky using nothing more than their eyes, but common tools for amateur astronomy include portable telescopes and binoculars.
Wikipedia: link
Other References:
http://www.amateurastronomy.com/
http://www.bambi.net/
