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Unformatted text preview: Astro 8-8-2009 Today • Eclipses • Ancient Greek Astronomy • Motion of stars Structure of Shadow • B can see no part of the light source • Complete Shadow • Umbra of shadow • A Can see top of source Penumbra • Partial Shadow • C Penumbra and Ring of light • D has a ring of light and penumbra Solar eclipse • X = Moon • Question? Why does Earth sit in shadow • If your far away you see partial eclipse, if your in the middle you see a total eclipse • Earth moon distance varies • Half the eclipses will have totality and half will have angular Total Eclipse (when it happens) • Only visable from a small region on earth • Most it can be is 200km wide • Earth distance varies • Earth rotates/Moon moves Umbra sweeps across surface of earth • Produces an eclipse track which is less than 200 km wide • It can be thousands of km long • Total eclipse last less than or eeual to 7 and 1/2 minutes • Anywhere else see partial or no eclipse Lunar Eclipse • X = Earth • Earth Shadow Big • Penumbral eclipse • Partial Eclipse...
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This note was uploaded on 12/01/2009 for the course ASTR 50800 at USC.