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Recording
information
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Brief history:
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Galileo used his eyes and
a pen in the 1600s
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Astronomers in the early
1900s used photographic plates (film)
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Modern astromoners use CCDs
(charge-coupled devices--think camcorder)
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Photographic plates and CCDs
allow for long exposure times (dim things become bright!)
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The eye records photons for
0.04 s before sending the picture to your brain
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Modern telescopes record
photons for 1800 s (1/2 hour) or more at a time
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CCDs record information directly
to the computer
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images from a WHOLE NIGHT
can be added together (get your brain to do that!)
CCD
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