Ancient

Transcript

[N 50 W ] AZ=310 N [S 50 E ] AZ=130 StoneHenge Special Configurations If the shape of the Earth was not spherical one would expect that sometimes the shape of the Earth’s shadow during a lunar eclipse would be something other than circular Spherical Earth Eratothenes angle measurement means the North South distance from Alexandria to Syrene is one fiftieth of the circumference of the Earth. It is fortunate that they share the same longitude. Eratothenes Aristarchus argued that if the Sun wasn’t much more distant than the Moon then the duration of crescent phases would be less than that of Gibbous phases Aristarchus Stellar Parallax The nearest stars are so distant that the ancients could not measure the parallax to the nearest star The celestial sphere interpreted mechanically, of these 4 concentric spheres all but the outermost is specific to the planet Mars Celestial Spheres Retrograde Motion The Deferent is fixed in space The Epicycle moves with centre on deferent Planet is stuck to Epicycle Ptolemy’s Model Eccentricity Ptolemaic Solar System The centres of the Epicycles of Mercury and Venus were attached to the Earth-Sun line Mercury and Venus