Hipparchus of Nicaea, who was born about 190 B.C., was a creative and talented Greek astronomer and mathematician. He founded trigonometry and scientific geography. He discovered precession of equinoxes and invented methods of fixing terrestrial positions by circles of latitude and longtitude. He located 850 stars and divided the stars that he could see into classes of apparent brightness. Hipparchus estimated the size and distance of the moon, found a way to predict eclipses, as well as calculating the length of the year to within 6 and a 1/2 minutes!