Plot: Film 1: As the world waits for Halley's Comet, a recently discovered diary written by a 17th-century merchant from Rye in Sussex reveals the feelings of a man caught up in a scientific revolution, when the new discipline of astronomy shouldered aside the age-old belief in astrology. Author Aubrey Burl, authority on stone circles, outlines new theories which suggest that the ancient peoples of Britain used the world's most famous circle as a lunar as well as a solar observatory