Astronomical Distance Scales

Some Common Distance Units: Light Year: the distance that light travels in one year (9.46 x 10^17 cm). Parsec (pc): 3.26 light years (or 3.086 x 10^18 cm).; also kiloparsec (kpc) = 1000 parsecs and megaparsec (Mpc) = 1,000,000 parsecs. Astronomical Unit (AU): the average separation of the earth and the sun (1.496 x 10^13 cm). Some Representative Distances: The Solar System is about 80 Astronomical Units in diameter. The...

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Hubble's constant (Hubble's Law)

The Hubble constant H is one of the most important numbers in cosmology because it may be used to estimate the size and age of the Universe. Hubble constant indicates the rate at which the universe is expanding. Although the Hubble "constant" is not really constant because it changes with time (and therefore should probably more properly be called the "Hubble parameter"). The Hubble constant is often written with a subscript "0"...

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