Deep in the Saudi Arabian desert, a group of robed men are peering into the sky, trying to spot the crescent moon that signifies the start of Ramadan. Their work is significant: an official sighting of the moon begins a month of fasting and prayer for millions of Muslims in Saudi Arabia, the home of Islam's holiest sites, and beyond. "I feel a great responsibility, before God above all, this is the most important thing," says Abdullah al-Khudairi, director of the Majmaah University Astronomical Observatory. IMAGES AND SOUNDBITES