Thursday, March 11, 2010

Astrophysics Notes

How is the Universe Organized?

· The force of gravity clusters matter at an astronomical scale.

· Clusters within the universe

o Solar Systems consist of: one or more stellar bodies, planets, moons, asteroids, comets, dwarf planets (e.g. Pluto, Eris), Kuiper-belt like debris

o Stellar clusters consist of solar systems

o Galaxies

o Galactic clusters consist of galaxies

· Stars and planets are different because stars emit light while planets reflect light.

· A light-year (ly) is the distance light travels in a year.

· 1 ly = (2.998 x 108 m/s) (3.156 x 107 s/yr) = 9.46 x 1015 m ≈ 1013 km

· Our galaxy is 100,000 ly wide, 2,000 ly tall

· Wein's Law for a blackbody radiator: λmax = (2.90 x 10-3) / T (kelvin)

· Gravity bends light

· Andromeda is 2 million ly away


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