Vedanga Jyotisha is one of the earliest treatises on Hindu astronomy. It is believed that Vedanga Jyotisha text was written in 1300 BCE. The work is a collection of separate treatises connected with Rig Veda and Yajur Veda. These treatises arose as a supplement to determine the auspicious time for performance of rites. The third shloka of Vedanga Jyotisha says “Vedas are revealed for the sake of performing Vedic rites, which are laid down in order of time. Hence, he who knows Jytoisha Shastra knows Yagna.
Vedanga Jyotisha is found in two recensions, namely, Rig Veda Jyotisha and Yajur Veda Jyotisha.
Rig Veda Jyotisha contains 36 shlokas. Yajur Veda Jyotisha contains 40 shlokas, of which thirty are common, with slight variations in wordings at places.
Vedanga Jyotisha is essentially an exposition on positional astronomy, a discipline dealing with astronomical delineation of sun and moon and their movement in the sky among constellations, division of time, and length of days during different parts of a year. However it does not state anything about planets. It gives an account of lunar days, semesters, seasons, etc. Arcajyotisha, a text that brought Vedanga Jyotisha to light, credits Vedanga Jyotisha to Lagadha Maharishi.
Vedanga Jyotisha was subjected to criticism by later mathematicians. Varahamihira had spoken lightly of the treatise under a pseudonym in order to avoid calumny by Vedic priests.
Brahmagupta later criticized the work vocally, asserting that the work was not by any divine personage. He also pointed to the mismatch in its account between the tropical year and the sidereal nakshatra division on which the lunar month was based.
Nevertheless, Vedanga Jyotisha is an important work that reveals the level of comprehension of astronomy at an early phase of Indian civilization.