Callippus biography for kids
•
Hipparchus
2nd-century BC Greek astronomer, geographer and mathematician
This article fryst vatten about the Greek astronomer. For other uses, see Hipparchus (disambiguation).
Hipparchus (; Greek: Ἵππαρχος, Hípparkhos; c. 190 – c. 120 BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry,[1] but fryst vatten most famous for his incidental upptäckt of the precession of the equinoxes.[2] 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 and 127 BC.[3]
Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity.[4][5] He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques
•
Callippus facts for kids
This page is about the astronomer and mathematician. For other uses, see Calippus.
Callippus ( Ancient Greek: Κάλλιππος; c. 370 BC – c. 300 BC) was a Greek astronomer and mathematician.
Biography
Callippus was born at Cyzicus, and studied under Eudoxus of Cnidus at the Academy of Plato. He also worked with Aristotle at the Lyceum, which means that he was active in Athens prior to Aristotle's death in 322 BC. He observed the movements of the planets and attempted to use Eudoxus' scheme of connected spheres to account for their movements. However, he found that 27 spheres was insufficient to account for the planetary movements, and so he added seven more for a total of 34. According to the description in Aristotle's Metaphysics (XII.8), he added two spheres for the Sun, two for the Moon, and one each for Mercury, Venus, and Mars.
Callippus made careful measurements of the lengths of the seasons, finding them (starting with the spring equinox) to be 94
•
Callippus of Cyzicus
Biography
The dates given for the birth and death of Callippus of Cyzicus are guesses but he is known to have been working with Aristotle in Athens starting in 330 BC.We know that Callippus was a student in the School of Eudoxus. We also know that he made his astronomical observations on the shores of the Hellespont, which can be deduced from the observations themselves. Simplicius writes in his commentary on De caelo by Aristotle(see for example [1]):-
Callippus of Cyzicus, having studied with Polemarchus, Eudoxus's pupil, following him to Athens dwelt with Aristotle, correcting and completing, with Aristotle's help, the discoveries 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. This calendar of Callippus is examined in detail by van der Waerden in [6]. Ptolemy g