Convert astronomical units (AU) to kilometers, miles, and light-years instantly. Uses IAU's official 2012 definition for professional-grade accuracy. Free calculator for students and astronomers.
An Astronomical Unit (AU) is a unit of length used to measure distances within our solar system. One AU is defined as the average distance between Earth and the Sun.
Astronomers use AU as a convenient way to express distances within our solar system. For example, Mercury is about 0.4 AU from the Sun, while Neptune is about 30 AU away.
For distances beyond our solar system, light-years are typically used instead of AU, as they represent much larger distances.
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