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foundations1

# foundations1 - 8 cm Distance to Sun = 1.5 x 10 13 cm =...

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Foundations of Astronomy The Metric System (used by scientists and foreigners) Mass 1 kilogram (kg) = 1000 grams (g) 100 kg = 220 lbs We tend to use mass and weight interchangeably, but weight depends on gravity. Distance 1 meter (m) = 100 centimeters (cm) Volume 1 cubic centimeter or 1 cm 3 (about the size of a sugar cube)

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Density Density = Mass (g / cm 3 ) Volume Densities of Common Substances Styrofoam 0.07 g / cm 3 Oak 0.7 Water 1.0 Average Rock 2.4 Iron 7.9 Lead 11.3 Gold 19.3
Temperature The Celsius Scale: 0 o C = freezing point of water 100 o C = boiling point of water The Kelvin Scale: T(K) = T( o C) + 273 o C "Absolute zero" 0 K = - 273 o C

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Angles 90 o 20 o 360 o , or 360 degrees, in a circle. 1 o = 60' or arcminutes 1' = 60" or arcseconds 1" = 1000 mas or milli-arcseconds
Scientific Notation Powers, or exponents, of 10: 100 = 10 2 (= 10 x 10) 1000 = 10 3 (= 10 x 10 x 10) 10 = 10 1 1 = 10 0 0.1 = 10 -1 0.007 = 7 x 10 -3 4000 x 0.002 = (4 x 10 3 ) x (2 x 10 -3 ) = 8 x 10 0 = 8 Add the exponents

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In astronomy, we deal with: 1. Vast distances - Radius of Earth = 6400 km = 6.4 x 10

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Unformatted text preview: 8 cm- Distance to Sun = 1.5 x 10 13 cm = 23500 Earth radii = 1 Astronomical Unit (AU)- Distance to next nearest star (Proxima Centauri): 270,000 AU = 4.3 "light years" (light year: distance light travels in one year, 9.5 x 10 12 km. Speed of light: c = 3 x 10 8 m/sec)- Size of Milky Way Galaxy: about 100,000 light years- Distance to next large galaxy (Andromeda): 2 x 10 6 light years 2. Huge masses:- Mass of Earth = 6 x 10 24 kg = 6 x 10 27 g = 1 M Earth (or 6000 billion billion tons)- Mass of Sun = 2 x 10 30 kg = 2 x 10 33 g = 1 M Sun = 1 "Solar Mass" = 333,000 M Earth- Mass of Milky Way galaxy: 6 x 10 11 M Sun 3. Long ages and times:- Age of Earth and Solar System: 4.5 billion years = 4.5 x 10 9 years- Lifetime of stars: about 10 6- 10 12 years- Age of universe: about 10 10 years 4. Very high and low temperatures:- An interstellar "molecular cloud": T = 10 K- Center of Sun: T = 1.5 x 10 7 K...
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