Astronomy: The Astronomical Unit

Astronomy: The Astronomical Unit
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Concepts & Techniques
The Astronomical Unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to 149597870700 m. Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012.

Commentary

Commentary

Source: Wikipedia (CC BY-SA)
The Astronomical Unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to 149597870700 m. Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars.

Commentary

Source: Internal
Why The Astronomical Unit matters: These foundational ideas and techniqu es are the tools astronomers use to measure, classify, and understand everything from nearby planets to the most distant galaxies. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. One au is approximately equivalent to 499 light-seconds.

Commentary

Source: Internal
Deep dive: The Astronomical Unit One au is approximately equivalent to 499 light-seconds. Source: https://en.wikipedia.org/wiki/Astronomical_unit (Wikipedia, CC BY-SA)