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Tuesday, February 10, 2015

What is the Astronomical Unit?

When describing distances on the scale of our Solar System, conventional units of measure are not conveniently sized. Miles are too small, and light years are too large, to permit easily compared numbers. For example, the distance between the Sun and Earth is about 93,000,000 miles; between the Sun and Pluto is about 3,700,000,000 miles. Comparing those two numbers, it is not easily seen that Pluto is about 40 times as far from the Sun as Earth is.

The Astronomical Unit (AU) represents a distance of Earth's average distance to the Sun, or about 93,000,000 miles.