There will be a full Moon Saturday night.  But not just any full Moon.  This Saturday September 29, 2012 at 11:18 p.m. Eastern Daylight Time, there is going to be a full Harvest Moon.

The Harvest Moon got its name in the days before electric lights, when farmers depended on the bright moonlight to extend the workday.  The light from the full Moon allowed them to gather their ripening crops in time for market.  The full Moon closest to the autumnal equinox became known as “The Harvest Moon”.
The word equinox comes from the Latin words for “equal night.” The fall and spring equinoxes are the only days of the year in which the Sun crosses the celestial equator and it is when daytime and nighttime are equal lengths everywhere on the planet.

The Discovery Channel explains the celestial equator, “Earth has its equator, the imaginary line that divides the planet into Northern and Southern hemispheres. The celestial equator is a similar imaginary circle around the celestial sphere, also known as the visible universe. The celestial equator divides the visible universe in two, creating the Northern and Southern celestial hemispheres.”