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Transcript
ASTR 1200 Announcements .. First Observatory Tuesday (9/2) 8:30pm .. (telescope dome building west of events center) AND Class will be in Fiske Planetarium on Tuesday (geodesic dome west of events center) Website http://casa.colorado.edu/~wcash/APS1200/APS1200.html Last Time We generally agreed: We really don’t know much about the nature of things. Science has a long way to go. We don’t understand consciousness and mostly think it is related to some phenomenon we haven’t yet begun to describe. We are probably not alone, but doubt the veracity of UFOs. Started Drake’s Equation. Scientific Notation an atomic nucleus is .000000000000001m a galaxy is 200000000000000000000 miles away So awkward we MUST use scientific notation an atomic nucleus is 10-15m a galaxy is 2x1019 miles away Scientific Notation (2) 1 = 100 10 = 101 100 = 102 1000 = 103 2000 = 2x103 .0035 = 3.5x10-3 0.1 = 10-1 .01 = 10-2 .001 = 10-3 etc (nx10p)x(mx10q) = (nxm)x10p+q 2.5x1019 x 3.0x10-5 = 7.5x1014 2.4 x1019 12 11 0 . 3 x 10 3 x 10 8 x107 Scientific Notation (3) Errors 2.5(±0.2)x1019 Doesn’t make sense to write 2.500(±0.2)x1019 Does make sense 2.500(±.002)x1019 Question Two hundred and forty thousand, when written in scientific notation is: a) 240,000 b) 240000 c) 240x103 d) 2.4x105 Drake’s Equation 1022 stars in the universe times 1 suitable planet per star times Probability of life times Probability of intelligent life given life We concluded that it is unlikely we are alone. Size of Things centimeters 100 101 102 104 105 108 109 1011 1013 1015 1018 1023 1025 1029 thumbtack baseball human football field kilometer Texas World Moon’s Orbit Distance to Sun Solar System Nearest Stars Milky Way Galaxy Nearest Galaxies Universe 10-2 10-4 10-7 10-8 10-15 sand grain DNA water molecule atom atomic nucleus