Work out distance in light years instantly with clear inputs, formula shown and shareable results.
A light year is the distance light covers in a Julian year, 9.4607e15 m. Proxima Centauri at 4.24 light years is 1.30 parsecs, 268,000 astronomical units or 4.01e13 km. Because the astronomical unit is Earth's orbital radius, it is the natural unit inside a solar system and hopelessly small between stars.
Light year
1 ly = 9.4607304725808e15 m
Parsec
1 pc = 3.0857e16 m = 3.2616 ly
A distance - how far light travels in a year. The confusion is common enough that it appears in film dialogue regularly.
Because parallax measurement gives distance in parsecs directly: one parsec is the distance at which Earth's orbit subtends one arcsecond.