Astronomical Units To Km
Calculator
Results
- Distance (million km)
- 778.567158
- Light travel time (minutes)
- 43.283674
- Distance (light years)
- 0.000082
Astronomy results
| Distance (million km) | 778.567158 |
| Light travel time (minutes) | 43.283674 |
| Distance (light years) | 0.000082 |
formula-map diagram
- Distance (million km)
- 778.567158
- Light travel time (minutes)
- 43.283674
- Distance (light years)
- 0.000082
Astronomical relationship
Formula
d = AU × 149 597 870 700 m= 778.56715827108
Note
This result is a simplified model: it applies the displayed textbook formula to the values you entered, assuming ideal spherical bodies, circular orbits, blackbody radiation and perfect optics, and ignoring atmospheric seeing, relativistic corrections beyond those stated, cosmological models and measurement uncertainty. Use published ephemerides and catalogue data for real observations.
More in Astronomy and space
See all →Frequently asked questions
What is an astronomical unit based on?+
One astronomical unit (AU) is defined as exactly 149,597,870.7 kilometers, a fixed value close to the average Earth-Sun distance. It was historically based on that distance but is now an exact defined constant, independent of Earth's slightly elliptical orbit.
How does the calculator convert AU to kilometers?+
It simply multiplies the number of astronomical units entered by the fixed constant of 149,597,870.7 km. There's no approximation involved since the AU is an internationally defined exact value.
Why isn't the AU just 'the distance from Earth to the Sun'?+
Earth's orbit is slightly elliptical, so its actual distance from the Sun varies between about 147.1 million km at perihelion and 152.1 million km at aphelion. The AU is fixed at the average, so it functions as a stable ruler even though Earth's real distance fluctuates around it.
When would I use AU instead of kilometers or light-years?+
AU is the natural unit for distances within a solar system, such as planetary orbits: Mars orbits at about 1.52 AU and Neptune at about 30 AU. Light-years and parsecs take over once you're comparing distances between different stars.
How many kilometers away is Neptune if it orbits at 30 AU?+
Multiplying 30 AU by 149,597,870.7 km gives roughly 4.49 billion kilometers, Neptune's approximate average distance from the Sun. This illustrates why AU is far more convenient than kilometers for describing solar-system-scale distances.