Halachic Times

Many observances in Jewish law are performed at specific times during the day. The calculation of these halachic times, known as zmanim (Hebrew for "times"), depends on the various astronomical phenomena of the day for the specific locale. Sunrise, sunset, the amount of time between them, and the sun's angular position before rising are all factors that determine the halachic times and "hours" of the day.

To find out more click on the link below:

http://www.chabad.org/calendar/zmanim.asp