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Unformatted text preview: the expansion of space. For now, use the figure above to see how a uniform expansion gives us the Hubble Law. Since space itself expands, all distances will increase by the same factor in the same amount of time. Galaxy (a) is 10 megaparsecs from galaxy (b) and galaxy (c) is 10 megaparsecs from galaxy (b). If the Hubble constant this time is 77 km/sec/Mpc, then galaxy (a) sees galaxy (b) moving at 770 kilometers/second away from it and galaxy (c) is moving away from galaxy (b) at 770 kilometers/second. Astronomers on galaxy (a) will see the galaxy (c) moving away at (770 + 770) kilometers/second = 1,540 kilometers/second, twice as fast as galaxy (b), because galaxy (c) is at a distance of (10 + 10) megaparsecs from galaxy (a), twice as far as galaxy (b)....
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