Hipparchus of Nicaea was a Greek astronomer who lived in the 2nd century BC, dying in 127Bc.
The foundations of astronomy were laid down by Hipparchus and survived 1500 years, until they were overthrown by the ideas of Copernicus.
Ancient Babylonian records brought back by Alexander the Great from his conquests helped Hipparchus to make his observations of the stars.
Hipparchus was the first astronomer to try to work out how far away the Sun is.
The first star catalogue, listing 850 stars, was put together by Hipparchus.
Hipparchus was also the first to identify the constellations systematically and to assess stars in terms of magnitude (see star brightness).
Hipparchus also discovered that the relative positions of the stars on the equinoxes (21 March and 21 December) slowly shift round, taking 26,000 years to return to their original place. This is called the ‘precession of the equinoxes’.
The mathematics of trigonometry is also thought to have been invented by Hipparchus.
Hipparchus carried out his observations at Rhodes. He was the first to pinpoint the geographical position of places by latitude and longitude.