AST101H1 Chapter Notes - Chapter 1: Celestial Equator, Right Ascension, Tropical Year
31 Dec 2017
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AST101H1 Full Course Notes
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S1. 2 celestial coordinates and motion in the sky. Celestial coordinates: function much like the coordinates of latitude and longitude on. Earth; we can use an object"s celestial coordinates to describe its precise location on the celestial sphere. Remember that the dates (equinoxes and solstices) are approximate because of the leap-year cycle and because a tropical year is not exactly 365. 25 days. You can find equinoxes or solstices with the aid of nearby bright stars. Declination (dec) is given as an angle describing an object"s position north or south of the celestial equator. Just as lines of latitude are parallel to earth"s equator, lines of declination are parallel to the celestial equator. Jest as earth"s equator has lat=0 , the celestial equator has dec=0 . Latitude is labeled north or south relative to the equator, while declination is labeled positive or negative.
