PHYS 284 Lecture Notes - Lecture 2: Celestial Equator, Northern Hemisphere, Astronomical Unit
5 Apr 2018
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Document Summary
More than 2000 stars may be visible to your naked eye. A constellation is a region of the sky with well-defined borders. The names and borders of the 88 official constellations were chosen in 1928 by members of the international astronomical unit (iau). The official names for the constellations visible in the northern hemisphere can be traced back to civilizations of the ancient middle east while southern hemisphere constellations carry the name of 17th century european explorers. Stars all appear to lie on the celestial sphere, but really lie at different distances. This is an illusion created by our lack of depth perception in space, but it is useful for mapping the sky. The north celestial pole is the point directly over earths north pole. The south celestial pole is the point directly over earths south pole. The celestial equator which is a projection of earths equator into spaces, makes a complete circle around the celestial sphere.
