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The red line indicates the Earth–Sun distance

An AU (Astronomical unit) is defined as the average distance from the Earth to the sun.
It is 149597870.691 km, or about 150 million kilometers (≈ 92.955807 million miles).

Within our Solar System, the AU is a practical way to illustrate distances.
For example, the distance from

  • Mercury to the Sun is 0.39 AU,
  • Jupiter to the Sun is 5.2 AU,
  • Pluto to the Sun is about 39.5 AU.

Celestial bodies with highly elliptical orbits have large variations in their distance from the Sun: at Chiron it varies from 8.5 to 18.9 AU. In one of the heavenly bodies with the most eccentric orbit, Sedna, the distance from the Sun varies from 76 to 892 AU.

This measure also influences the duration of a planet in a zodiac sign. Given the distance of 1 AU for the Earth, the time for Jupiter to run through a zodiac sign is about a year.

The Sun and eight planets of the Solar System[1]

See also


Notes and References

  1. With sizes as well as distances shown to scale