Cleostratus

Cleostratus (; b. c. 520 BC; d. possibly 432 BC) was an astronomer of ancient Greece. He was a native of Tenedos. He is believed by ancient historians to have introduced the zodiac (beginning with Aries and Sagittarius) and the solar calendar. According to J. Webb, Cleostratus took his ideas from the Babylonians.

There is little primary material to credit any person with the creation or design of the Zodiac. Historical research into this has shown translation issues and coincidences including the Tenedos connection with the Philosopher Thales. Historical writings also refer to Cleostratus as a means of establishing a tradition of authority of Greek accomplishments. Continuation of Babylonian cycles is considered not to be scientific progress as the Greeks improved the accuracy of their cycles, only exercises in the art of combining days, months, and years, of which the relative mean durations had been learned from Babylon. The Greeks may have established a similar system, as other cultures had too, independently of the Babylonians. However, most agree that there can never be a definite answer for the argument concerning who established the first known system in the west.