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History of the Earth Chapter 9. Syst ème International (SI). Adopted in 1960 Fundamental Units of measurement meter, gram, second ampere, radian, steradian mole, candela, kelvin Scientific Notation based on powers of 10 3.67 X 10 4 = 36,700. Powers of 10 Logarithmic Scale.
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Système International (SI) • Adopted in 1960 • Fundamental Units of measurement • meter, gram, second • ampere, radian, steradian • mole, candela, kelvin • Scientific Notation based on powers of 10 • 3.67 X 104 = 36,700
Powers of 10Logarithmic Scale • 100 = 1 • 101 = 10 10-1 = .1 • 102 = 100 10-2 = .01 c • centi • 103 = 1,000 k 10-3 = .001 m • kilo milli • 106 = Million M 10-6 millionth μ • mega micro • 109 = Billion G 10-9 billionth n • giganano
How old is the Earth? • Numerous mythical or religious accounts • Babylonian, Druidic, Egyptian, Hebraic, • Hindu, Mayan, Norse, Sumerian • 4th century Saint Augustine ≈ 6 ka • 1654 James Usher • The universe separated from the void at 9 A.M. on Sunday October 23, 4004 BC (bce) • 1956 Clair Patterson Pb/Pb ≈ 4.56 Ga
Interstellar Stuff • Calculations suggest that there is lots of stuff not in observed bodies • Stars form where stuff is compressed at the leading edge of a galaxy • Not all stuff into stars • Stuff not uniformly distributed
Younger stars on leading edge Older stars on training edge Knots of stuff yet to be compresses Knots of stuff from stars that went bad Compression on leading edge
Controls of Stellar Fusion • Fuel • Pressure • Temperature
Meteor Crater • 49 Ka
Shield Craton Platform