Size scales of the Universe
Comment: We use two different length scales in astronomy when dealing with cosmology. The scales are the light year, the distance a beam of light travels in 1 year or
1 light year = 9.5 trillion kilometers ~ 5.9 trillion miles.
The other length scale used is the parallax second or more commonly the parsec which is
1 parsec = 3.08×1013 kilometers ~ 3.24 light years
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