Euctemon (Euktemon)

Lived and worked in Athens. E. - The first astronomer, who introduced the tropical division of the Zodiac. Based on observations of the summer solstice in 432 g. BC, he published parapegmu, ie. star calendar, which were marked by the equinox and solstice, the annual rising and setting of the fixed stars and the corresponding weather guidance. He divided the solar year of 12 "months", defined by the 12 signs of the Zodiac. Sunny year E. began with the summer solstice. The first five "months" were 31 each day, following seven - 30 days. Consequently, E. believed that the Sun is one part of the zodiac at a constant speed of 30 б° for 31 days, and the remainder - at a speed of 30 б° for 30 days.

Literature:
1. Van der Waerden B. Science awakening II. The Birth of Astronomy.
2. Baigent M., Campion N., Harvey C. Mundane Astrology.