4 ms·

Interesting, what do you mean he "understood he was in the Northern Hemisphere"? There are an infinite number of possible ways to divide a sphere into hemispher

• einhverfr 13y ago
  If you read Tetrabiblos, he describes Africans (presumably from Nubia) as "burned by the sun" and explains this due to the fact that the "sun is over their heads." While the Africans are too dark, he doesn't think much of Northern Europeans either, who he says look sickly and pale because the bear is over their heads. Alexandria, being the center of the world, and neither too light nor too dark, nor too far East nor too far West, is best of course in his eyes. In Almagest he describes two things. The first is the shape of the earth, where he points out that it must be a sphere because of the changes in inclination of the moon and stars as you head North and South, and the changes in times of lunar eclipses when you head East to West. His descriptions of the rotation of the earth and the position of the sun relative to the earth leave no doubt that he was aware of Northern and Southern hemispheres. > Was he aware that the seasons were the result of the Earth's tilt and that they would be swapped in the other hemisphere as defined by that tilt? It's a little hard. Alexandria's sub-tropical. He does mention the inclination of the earth relative to the equator though, iirc, in Almagest.