Astronomical distances span such enormous ranges that different units are used depending on scale — astronomical units (AU) for the solar system, light-years and parsecs for interstellar and galactic distances.
Astronomical distances span such enormous ranges that different units are used depending on scale — astronomical units (AU) for the solar system, light-years and parsecs for interstellar and galactic distances. This calculator converts a distance in AU into all three.
Neptune orbits at about 30.1 AU. Distance = 30.1 × 1.495978707×10⁸ ≈ 4.503×10⁹ km ≈ 0.000476 ly ≈ 0.000146 pc.
Common astronomical units include kilometers, astronomical units (AU), light-years, and parsecs.
One AU is the average distance from Earth to the Sun, about 149.6 million kilometers — a convenient yardstick for distances within our solar system.
A light-year is the distance light travels in one year (~9.46 trillion km); a parsec is a unit based on parallax measurement, equal to about 3.26 light-years.