Person: Callippus Of Cyzicus
Callippus was a Greek astronomer who made accurate determinations of the lengths of the seasons and constructed a calendarused by all later astronomers.
Mathematical Profile (Excerpt):
 We know that Callippus was a student in the School of Eudoxus.
 Callippus made accurate determinations of the lengths of the seasons and constructed a 76 year cycle comprising 940 months to harmonise the solar and lunar years which was adopted in 330 BC and used by all later astronomers.
 Instead of having totals of 440 hollow and 500 full months, Callippus adopted 441 hollow and 499 full, thus reducing the length of four Metonic cycles by one day.
 Callippus introduced a system of 34 spheres to explain the motions of the heavenly bodies.
 Other contributions of Callippus to mathematical astronomy included his observation of the inequality in the lengths of the seasons.
Born about 370 BC, Cyzicus, Asia Minor (now Turkey). Died about 310 BC.
View full biography at MacTutor
Tags relevant for this person:
Ancient Greek, Astronomy, Origin Turkey, Physics
Mentioned in:
Epochs: 1 2
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References
Adapted from other CC BYSA 4.0 Sources:
 Oâ€™Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive