ASTR-1010 Lecture Notes - Lecture 16: Angaur, Right Ascension, Declination
6 Oct 2016
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Constellations are regions of the sky: 88 constellations fill the entire sky. How do we locate objects in the sky: know your reference points, locate an object by its altitude (above horizon) and direction (along horizon) Angular measurements: full circle: 360 degrees, 1 degree = 60" (arcminutes, 1" = 60 (arcseconds) Q: the anguar size of your finger at arm"s length is about 1 degree. how many arcseconds is that: 3600. Celestial coordinates: declination: north or south of the celestial equator, right ascension: east or west of vernal equinox. Why do stars rise and set: earth rotates from west to east, stars appear to move from east to west, dirunal motion. Stars near the north celestial pole are circumpolar and never set. We cannot see stars near the south celestial pole. All other stars (and sun, moon, planets) rise in east and set in west.
