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Picture of Hipparchus
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Hipparchus

Hipparchus was a Greek astronomer who lived between 190-120 B.C. He created the first accurate star map and kept a catalogue of over 850 stars with their relative magnitudes.

The system of epicycles describing planetary motion was developed by Hipparchus, and helped preserve the geocentric model of the universe. His estimates of the moon's size and distance relative to Earth were also remarkably accurate for his time.

Hipparchus is considered the founder of trigonometry for his work with the lengths of chords traced out by angles in a circle. His table of chords was the forerunner to modern trig tables.


Last modified July 25, 2001 by Jennifer Bergman.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA