ASTRON 1F03 Lecture Notes - Lecture 1: Celestial Equator, Ecliptic, Northern Hemisphere
18 Dec 2015
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Document Summary
Planets don"t appear to move among the stars. The stars that make up orion are at different distances. As viewed from the north pole, earth rotates counterclockwise on its axis. The earth"s spin makes the sky appear to revolve around us. The celestial sphere is a projection of earth"s axes and equator into space. Points on the sphere do not correspond to any real distance individual stars are at different distances. It rotates around the north and south celestial poles each day. Ecliptic: path of the sun inclined 23. 5 degrees to equator. At earth"s north pole, we would see half the celestial sphere. No stars rise or set, they are all circumpolar. Observers can never see the south celestial pole. At earth"s equator, all stars rise and set. Observers can see the entire celestial sphere as it rotates. At an intermediate latitude on earth, one pole is above the horizon. The celestial poles are on the northern and southern horizons.
