Transcription: Hipparchus was a Greek astronomer whose achievements included tracking the Sun's path in the sky. From observing the star Spica in the constellation of Virgo, he discovered the precession of the equinoxes and apparent shifting of the stars over many centuries. He also calculated the solar year to within seven minutes of its actual length and estimated the distances of the Sun and the Moon from the Earth. His work remained largely unchallenged for centuries after his death, and his The catalogue of 850 stars completed in 129 BC was still in use 1800 years later.
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