An Astronomical Unit (AU) is a distance unit
meant to convey the distance between the Earth and the Sun,
or more specifically the mean between the Earth's orbit's
Aphelion and Perihelion. However, it is now fixed at
149597870700 meters, and only considered a general
term for the Earth-Sun distance. An AU is equivalent to:
- about 150 million km.
- about 93 million miles.
- 4.848 × 10-6 Parsecs (pc).
- 1.581 × 10-5 light years.
Some distances in AU:
| 0.0000026AU || distance from Earth to Moon |
| 0.0000047AU || diameter of the Sun |
| 5.2AU || radius of Jupiter's orbit |
| 30AU || radius of Neptune's orbit |
| 276173AU || distance to Alpha Centauri |
| 1.6 billion AU || distance to Galactic Center |
| 1604 billion AU || distance to Andromeda (M31) |
Spitzer Space Telescope (SST)