Hipparchus
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Hipparchus was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hipp
Illustration based on a 19th century engraved amethyst from the Poniatowski gem collection
The figure on the left may be Hipparchus, from Raphael’s fresco The School of Athens
A 19th century artist's impression of Hipparchus
Hipparcos satellite in the Large Solar Simulator, ESTEC, February 1988
Axial precession
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In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orb
Hipparchus
…Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hipparchus was born in Nicaea, Bithynia, and probably died on the island of Rhodes, Greece. He is known to have been a working astronomer between 162…
"Table indicating the longitude of three stars observed at different times." Compiled by Adriaan Metius, 1624.
Precessional movement as seen from 'outside' the celestial sphere
Marine sandglass MMM