(1st millennium BCE): He had written the earliest astronomical text, Vedanga Jyotica,which provides details on SEVERAL astronomical attributes, generally applied for timing social and religious events. It also explains astronomical calculations and calendar studies, and establishes rules for empirical observation. Vedanga Jyotica has connections with Indian astrology and mentions important aspects of the time and seasons, including LUNAR months, SOLAR months, and their adjustment by a lunar leap month of Adhimasa. Ritus and Yugas are also described. It also mentions of 27 constellations, eclipses, seven planets and 12 signs of the zodiac known at that time. Aryabhata (476–550 CE): Aryabhata was the AUTHOR of the Aryabhatiya and the Aryabhatasiddhanta. Aryabhata explicitly mentioned that the earth rotates about its axis, thereby causing what appears to be an apparent westward motion of the stars. Aryabhata also mentioned that reflected sunlight is the CAUSE behind the shining of the moon. Aryabhata’s followers were particularly strong in South India, where his principles of the diurnal rotation of the earth, among others, were followed and a number of secondary works were based on them.