The Hajj:
The Hajj formally begins on the eighth day of Dhul-Hijjah (Zul-Hijjah) - the 12th month of the Muslim lunar calendar. "Islamic months begin at sunset on the day of visual sighting of the lunar crescent [following the new moon]... Although it is possible to calculate the position of the moon in the sky with high precision, it is often difficult to predict if a crescent will be visible from a particular location... Usually the moon has to be at least 15 hours old before it can be seen from somewhere on earth." 3

On this first day of the Hajj, the pilgrims walk a few miles to Mina and camp there overnight. This will occur about 2000-MAR-14. It falls on a date about 11 days earlier each year.

The pilgrims spend the "Day of Arafah" (ninth day of Dhul-Hijjah) in Arafah, an empty plain. They commit the entire day to supplication and devotion. In the evening, they move to Muzdalifa. They camp there overnight and offer various prayers.

On the tenth day of Dhul-Hijjah, they return to Mina and throw seven pebbles at a pillar that symbolizes Satan's temptation of Abraham. (The Qur'an describes how Satan tried to persuade Abraham to not ritually murder his son Ishmael, as commanded by God). The pilgrims then sacrifice a sheep, recalling how Abraham sacrificed a sheep that God had provided in place of his son. The meat is distributed to friends, relative and the poor. Afterwards, they return to Mecca and perform a final tawaf and sa'i. They symbolize the completion of the Hajj by cutting their hair.

Muslims worldwide gather for communal prayers on the first day of Id al-Adha (Eid-ul-Adha) -- the Feast of Sacrifice or Day of Sacrifice. The first day of this celebration is held on the 10th day of Duhl-Hijja, the last month of the Muslim year. This is the second of the two major Muslim annual holidays. In most areas, this event is celebrated over several days.
http://www.religioustolerance.org/isla1.htm

Sounds like quite the party! :stoned: