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Convert between kilometers, AU, light years, and parsecs for space distance calculations
| Unit | Kilometers | AU | Light Years | Parsecs |
|---|---|---|---|---|
| 1 km | 1.000e+0 | 6.685e-9 | 1.057e-13 | 3.241e-14 |
| 1 AU | 1.496e+8 | 1.000e+0 | 1.581e-5 | 4.848e-6 |
| 1 ly | 9.461e+12 | 6.324e+4 | 1.000e+0 | 3.066e-1 |
| 1 pc | 3.086e+13 | 2.063e+5 | 3.262e+0 | 1.000e+0 |
| Distance | km | AU | ly | pc |
|---|---|---|---|---|
| Earth to Moon | 3.84e+5 | 2.57e-3 | 4.06e-8 | 1.25e-8 |
| Earth to Sun | 1.50e+8 | 1.00e+0 | 1.58e-5 | 4.85e-6 |
| Sun to Neptune | 4.50e+9 | 3.01e+1 | 4.75e-4 | 1.46e-4 |
| Sun to Proxima Centauri | 4.00e+13 | 2.68e+5 | 4.24e+0 | 1.30e+0 |
| Sun to Galactic Center | 2.45e+17 | 1.64e+9 | 2.60e+4 | 7.97e+3 |
Astronomical distances span such enormous scales that conventional units like meters or kilometers become impractical. Astronomers use specialized units suited to different scales: kilometers for nearby objects, astronomical units (AU) for solar system distances, light years for interstellar distances, and parsecs for stellar and galactic measurements. An astronomical unit represents Earth's average distance from the Sun (149.6 million km), while a light year is the distance light travels in one year (9.46 trillion km). A parsec, derived from "parallax arcsecond," equals about 3.26 light years and relates directly to stellar parallax measurements. This multi-unit converter allows seamless translation between these scales, helping astronomers, students, and space enthusiasts understand cosmic distances in various contexts.
This multi-unit converter simplifies astronomical distance conversions:
Use kilometers for planets and nearby objects, AU for solar system distances, light years for nearby stars, and parsecs for professional stellar distance measurements.
Each unit is optimized for a particular scale. Using kilometers for galaxy distances would result in impossibly large numbers, while using parsecs for planetary distances would give tiny fractions.
The observable universe extends about 93 billion light years (28.5 billion parsecs) in diameter. Astronomers typically use megaparsecs or gigaparsecs for such cosmic distances.
Our converter uses internationally accepted conversion factors from the International Astronomical Union, providing accuracy suitable for educational and most research purposes.
Yes! Simply enter the distance in any unit. For example, Mars is about 1.5 AU from the Sun, which our converter will show in kilometers, light years, and parsecs.
A light year is the distance light travels in one year (9.46 trillion km), while a parsec is about 3.26 light years and is based on parallax measurements of stellar positions.
Parsecs relate directly to the parallax method used to measure stellar distances. When a star's parallax is 1 arcsecond, it's exactly 1 parsec away, making calculations more straightforward.