Monday, September 23, 2013

Hipparchus of Rhodes (190-120 BC)

Known for his methodical observational skills and innovation mind, Hipparchus did much to advance the field of astronomy and to transform it into a quantitative science.

Many of the astronomical calculations were made accessible through the trigonometric formulas of Hipparchus; he may also have been the first to use spherical trigonometry and stereographic projection. 

Hipparchus introduced 360° angle measure and sexagesimal arithmetic from Babylon, invented a stellar magnitude scale that still b used in updated form today.

Hipparchus was best known for his discovery of the precession of the equinoxes.  This find allowed him to calculate the length of the year.

His birthplace may have been in Nicaea which is now in northwestern Turkey. It is believed he spent much of his career in Rhodes where he built an observatory.

At Rhodes, he identified 850 stars and charting their movements and relative brightness.

Hipparchus studied the precession of the equinoxes, the circuit that the earth makes over thousand years as it rotates on its axis.

He was most active between 147 BC and 127 BC which are known to be the dates of his first and last astronomical observations.
Hipparchus of Rhodes (190-120 BC)

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