ASTR 170B1 Lecture Notes - Lecture 2: True North, Celestial Sphere, Declination
28 Sep 2016
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Document Summary
And irregular motions like comet and meteors. Observations since ancient times - the roots of astronomy. Useful reference points for astronomers, like a roadmap in the sky. Northern constellations have latinized names often from ancient mythology. Orion, cygnus, perseo, andr meda, ursa major, canis major. Southern constellations modern invented by europeans after magellan. Individual stars, especially bright ones readily visible to the naked eye, have been named. Stars visible at night change with the seasons. Implication: the sun moves with respect to the stars. Stars will always appear to move east to west across the sky in a night. Center of circle is a point called north celestial pole in no. Star called polaris (the north star) lies very close to ncp. Around the stationary north star. circumpolar stars ( they never rise or set they are always above the horizon. Celestial sphere: imaginary sphere outside earth with stars pasted on it.
