Hipparchus and Trigonometry Hipparchus founded trigonometry, by computing the first trigonometric function, namely, a chord tables.

Hipparchus on a Poem The sole surviving work of Hipparchus is known as the Commentary on the Phenomena of Aratus and Eudoxus. It described a calendar with references to the risings and settings of constellations.

Life Hipparchus is mainly known from Ptolemy’s Alagest. He is also known by Strabo’s Geographia and also from Pliny’s Naturalis Historia. He was born in Nicaea, which is present day Turkey. Hipparchus must have lived sometime after 127 BC.

Life Hipparchus is believed to have died on the island of Rhode, where he spent most of his later life. The main original works of Hipparchus have been lost over the year. It is known that he created a celestial globe. There are 2 nd and 3 rd centuries coins made in Hipparchus’ honor in Bithynia.

Life Hipparchus is recognized as the originator and fathor of astronomy. It is believed that Ptolemy originated his idea’s from Hipparchus’ and just perfected them.

Accomplishments Hipparchus is known for many things: -Astronomical instruments and astrometry -Geography -Star catalogue -Lunar and solar theory -Geometry and Trigonometry

Geometry and Trigonometry Hipparchus is the first recognized mathematician who complied a Trigonometry table. He used this table to compute the behavior of the orbits of the Moon and the Sun. He described this behavior in the [chord(A) = sin(A/2)] equation. He explained his work in a now lost, Toon en kuklooi euteioon (Of Lines Inside a Circle).

Lunar and Solar Theory Hipparchus studied and had theories over: -Motion of the Moon -Orbit of the Moon -Apparent motion of the Sun -Orbit of the Sun -Distance and sizes of the Moon and Sun -Eclipses

Astronomical Instruments and Astrometry Hipparchus invented and improved many astronomical instruments, which were used for naked- eye observations. He invented the astrolabe, which was to measure the geographical latitude and time by observing stars. He also invented a dipotra, which measured the apparent diameter of the sun and moon. It was a 4- foot rod with a scale, a sighting hole at one end and a a wedge that could be moved along the rod to exactly obscure the disk of the Sun or the Moon.

Geography Hipparchus was the first to apply mathematical rigor to the determination of the latitude and longitude of places on the Earth. He also made detailed corrections to the locations and distances mentioned by Eratosthenes.

Star Catalogue Hipparchus created a catalogue with the coordinates of about 1,000 stars. In this sculpture, the atlas the man is holding features the positions of the stars, is from Hipparchus’ star catalogue.

Conclusion The Greek Astronomer Hipparchus is credited with introducing numerical data from observations into geometric models and discovering the precession of the equinoxes. Little of his work survives, but Ptolemy considered him his most important predecessor.