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Q:
Is the universe expanding at about 65 miles per second?
A:
You are probably referring to the recent determinations of that
the Hubble constant, which gives the rate of expansion of the
universe, is 65. However, the units are not miles per hour, but
kilometers per second per megaparsec. A megaparsec is a unit of
distance equal to 3.26 million light years. If the Hubble
constant is 65, then a galaxy 3.26 million light years away will
be receding at a speed of 65 kilometers per second. One that is
ten times further away, will be receding at a speed ten times
greater, 650 kilometers per second. On our web site we use a
Hubble constant of 60 kilometers per second, which is within the
margin of error of the recent estimates. See also: http://chandra.harvard.edu/photo/cosmic_distance.html
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