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AU - Astronomical Unit

An AU is the average distance between the center of the Earth and the center of the Sun, which is about 150 million kilometers, or 93 million miles.

The current value is defined to be 149,597,870,691 meters, which is 92,955,807 miles.

The official symbol for this unit is ua, but in most English language speaking countries it is written as AU.

Astronomers use the AU in their calculations for planetary motion. Since the calculations are the same regardless of the distance unit used, their predictions will remain valid even if future scientists determine a different value for the distance between the Sun and Earth.

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