Hipparchus

Hipparchus was born in 190 BC in Nicaea, Bithynia which is presently known as Iznik and located in modern day Turkey.

Hipparchus used to collect the records of the local weather conditions that were prevalent throughout the year when he was a young man living in Bithynia. The ‘weather calendars’ had been produced by various Greek astronomers since the 4th century BC which helped him understand the synchronization of the rains, winds, storms, seasons with the sun, moon and the constellations.

He began his scientific career in Bithynia and moved to Rhodes sometime before 141 BC.

He also worked in Alexandria for some time where he made some more observations. He probably had communications with observers in Alexandria and astronomers in Babylon who provided him with a lot of information on the time when equinoxes occurred.

He spent most of his adult life on the island of Rhodes to carry out various astronomical observations. According to Ptolemy, three observations were made from 162 to 158 BC and about twenty or more of these observations were made on specific dates ranging from 147 to 127 BC.

Out of these twenty or so observations made by Hipparchus, the first one was made on September 26 or 27, 147 BC on the autumnal equinox.

Out of the numerous works written by Hipparchus the only surviving one available today is a commentary on a poem written by Aratus from the 3rd century titled ‘Commentary on the Phainomena of Eudoxus and Aratus’.