Celestial Mechanics: The Early Years

    Early Greeks had a surprisingly sophisticated view of our Solar System

  • Aristarchus of Samos (c. 270 B.C.): Advocated the view that the Earth revolved around the Sun. Used geometry to estimate relative distances of the Sun and Moon, and proportions of the Earth and Moon.

  • Eratosthenes (c. 200 B.C.): Measured the circumference of the Earth to high precision by noting the Sun’s elevation at different locations in Egypt on the same days.

  • Ptolemy (c. A.D. 100): Culmination of the Geocentric View of the Cosmos. The Earth was at the center, with the Sun, Moon, planets and stars revolving around it on "crystalline spheres". THE going model for another 15 centuries!

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