Lecture07.doc - Celestial Sphere Reference Points Observer...

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Adaptive Optics Earth’s atmosphere limits telescope resolution to  something  much less than theoretical value. This can be countered by measuring the  distortion  caused by “seeing” which is the same as  “twinkling.” Use laser and rapidly deformable thin mirrors on  a  telescope.  Why is the sky blue? Blue light is scattered preferentially by the  molecules in the  Earth’s atmosphere. Why are sunsets red? All but the red light is scattered away from the  Sun by  molecules and dust absorption. Dust reflects some of this light so the sky appears red, too. Naked Eye Astronomy What is in the sky?  Sun Moon Stars  Planets Meteors Comets Milky Way
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Some move, some don’t - Long ago it was seen that the sky looks  different at different locations on earth, and at different times.  Therefore can use the sky to measure locations on earth and time.  Need coordinate system, reference points. 
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Unformatted text preview: Celestial Sphere Reference Points Observer based - different for every observer horizon - where the sky meets the sea zenith - point directly overhead (easy to measure) meridian - great circle (i.e. straight line) connecting north and the zenith Sky based - same for every observer Celestial Pole (in Berkeley - North CP) - the point on the sky around which all stars turn (Does Earth rotate or does the sky? - How do you know?) Celestial Equator - the great circle that is 90 O from the celestial poles Right Ascension (RA) - great circles through the north and south celestial poles (like longitude on the Earth) Declination (Dec) - lines (but not straight ones) at regular intervals perpendicular to lines of RA (like latitude on the Earth) Constellations...
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Lecture07.doc - Celestial Sphere Reference Points Observer...

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