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Unformatted text preview: 1 Extraterrestrial Life: Spring 2008 Cosmological context of stars and planets Architecture of the Solar System: Sun (mass 2 x 10 30 kg - 1 Solar mass) 4 rocky, terrestrial planets in the inner Solar System (Earth: 6 x 10 24 kg) 2 gas giants (Jupiter, Saturn), mostly made of gas but not of Solar composition 2 ice giants (Uranus, Neptune) - about 10 Earth mass cores with few Earth mass atmospheres small bodies (asteroids, comets, Kuiper belt) Scale: mean distance between Earth - Sun is deFned as 1 astronomical unit = 149,598,000 km Size of the Solar System is ~50 AU Extraterrestrial Life: Spring 2008 Distances to stars are measured in light years - distance that light travels in 1 year. Speed of light c = 300,000 km/s In one year there are 365.25 x 24 x 3600 s = 3.16 x 10 7 s 1 light year = 3.0 x 10 5 km/s x 3.16 x 10 7 s = 9.5 x 10 12 km about 60,000 AU Nearest star is ~4 light years away - 240,000 AU Solar System is extremely small on the scale of distances to other stars Extraterrestrial Life: Spring 2008...
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This note was uploaded on 08/31/2009 for the course GEOL 3300 taught by Professor Staff during the Spring '08 term at Colorado.
- Spring '08