Convert between astronomical distance units including AU, kilometers, miles, light-seconds, light-minutes, light-years, and parsecs.
The Astronomical Unit (AU) is defined as exactly 149,597,870.700 kilometers. It is approximately the average Earth-Sun distance and is commonly used for solar system scales.
The AU became an exact defined constant in 2012, which removed measurement ambiguity and made conversions cleaner.
Astronomical Units
Best for solar system distances such as planets, asteroids, and spacecraft ranges.
Light-years
Best for interstellar and galactic-scale distances in more public-facing explanations.
Parsecs
Common in professional astronomy because they connect directly to parallax-based distance measurements.
| Object | AU | Light-years | Light-time |
|---|---|---|---|
| Moon (from Earth) | 0.00257 | 4.07×10⁻⁸ | 1.28 sec |
| Sun (from Earth) | 1 | 1.58×10⁻⁵ | 8.3 min |
| Mars (average) | 1.52 | 2.40×10⁻⁵ | 12.7 min |
| Jupiter (average) | 5.2 | 8.22×10⁻⁵ | 43 min |
| Neptune (average) | 30.1 | 4.76×10⁻⁴ | 4.2 hrs |
| Voyager 1 | 165 | 2.61×10⁻³ | 23 hrs |
| Proxima Centauri | 268,000 | 4.24 | 4.24 yrs |
| Center of Milky Way | 1.700000e+9 | 27,000 | 27,000 yrs |
| Andromeda Galaxy | 1.590000e+11 | 2.54 million | 2.54 Myr |
Parsecs tie directly to parallax measurements, which makes them practical in observational astronomy.
Earth's orbit is slightly elliptical, so the actual distance changes through the year. The AU corresponds to the orbital scale rather than one exact daily distance.
A light-second is the distance light travels in one second. It is useful for communication-delay thinking within the Earth-Moon system and nearby planetary space.
A distance of 0.37 AU is a useful example for close Mars opposition scales.
Converted Values
Context
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