Hipparchus( Outstanding ancient Greek astronomer)
Comments for Hipparchus
(Hipparchos; ca. 190 - 125 years. BC)
outstanding ancient Greek astronomer, who is also often credited with reforming astrology. Conducted the first systematic astronomical observations. Observation of a new star (134 g. BC) led him to create the star catalog, which was used later by Ptolemy. This directory contains the provisions of 850 stars, separated by the degree of brightness by 6 stellar magnitudes. By comparison, he found the location of points of stars to those that have been identified in other catalogs, D. discovered the phenomenon of precession of the equinoxes. He studied the apparent motion of the sun and the moon and made the table this motion, . he calculated the anomalies of solar motion and explained to them, . that the Sun is eccentric path around the Earth, calculated with great precision the inclination of the ecliptic; determined with an error less than 5% of the distance from Earth to the Moon and accurately - from the Earth to the Sun, calculated as the length of the tropical year is 365 days 5 hours 55 mins (the true length -- 365 d 5 h 48 min 46 s) and duration of the synodic month, . getting value 29 days 12 hours 44 min 2.5 sec, . is only 1 with less than true; developed a theory of eclipses; introduced geographic coordinates - latitude and longitude; laid the foundations of trigonometry, . particularly, . dividing the circle into 360 б╟, . subdivided, . in turn, . in minutes and seconds; invented new tools,
. Works G. did not reach us, except for comments on an astrological poem Arata. Information about the work of Mr.. presented in the book of Ptolemy K. "Almagest".
G. called the father of scientific astronomy. Most of his research he conducted at the Alexandria observatory, built on the island of Samos. G. first fixed orbital plane of the lunar orbit to the ecliptic plane - about 5 б╟. He also discovered that the nodes of the Moon continuously move from east to west, making a complete revolution in 18.6 years. G. found that the line of apses of the lunar orbit is mobile and makes a complete turn for the 8.85 g. (cycle of Lilith).