Enter a distance (in AU, km, or miles) into the calculator to determine the equivalent earth years.
AU to Years Formula
The following formula is used to calculate the average speed from a distance (expressed in AU) and a time (years).
v = \frac{D}{T}Variables:
- v is the average speed (e.g., AU/year)
- D is the distance traveled (measured in astronomical units, AU)
- T is the time in years
To calculate the average speed, divide the distance traveled (in AU) by the time (in years). For a nearly circular orbit with semi-major axis (or radius) a, the distance traveled in one full orbit is approximately D ≈ 2πa, so the mean orbital speed is v ≈ 2πa/T.
| Distance (AU) | Years at 0.5 AU/yr | Years at 1 AU/yr | Years at 2 AU/yr | Years at 3 AU/yr | Years at 5 AU/yr |
|---|---|---|---|---|---|
| 0.100 | 0.200 | 0.100 | 0.050 | 0.033 | 0.020 |
| 0.250 | 0.500 | 0.250 | 0.125 | 0.083 | 0.050 |
| 0.500 | 1.000 | 0.500 | 0.250 | 0.167 | 0.100 |
| 1.000 | 2.000 | 1.000 | 0.500 | 0.333 | 0.200 |
| 2.000 | 4.000 | 2.000 | 1.000 | 0.667 | 0.400 |
| 3.000 | 6.000 | 3.000 | 1.500 | 1.000 | 0.600 |
| 4.000 | 8.000 | 4.000 | 2.000 | 1.333 | 0.800 |
| 5.000 | 10.000 | 5.000 | 2.500 | 1.667 | 1.000 |
| 6.283 | 12.566 | 6.283 | 3.142 | 2.094 | 1.257 |
| 9.579 | 19.158 | 9.579 | 4.790 | 3.193 | 1.916 |
| 10.000 | 20.000 | 10.000 | 5.000 | 3.333 | 2.000 |
| 15.000 | 30.000 | 15.000 | 7.500 | 5.000 | 3.000 |
| 20.000 | 40.000 | 20.000 | 10.000 | 6.667 | 4.000 |
| 25.000 | 50.000 | 25.000 | 12.500 | 8.333 | 5.000 |
| 30.000 | 60.000 | 30.000 | 15.000 | 10.000 | 6.000 |
| 32.696 | 65.392 | 32.696 | 16.348 | 10.899 | 6.539 |
| 40.000 | 80.000 | 40.000 | 20.000 | 13.333 | 8.000 |
| 50.000 | 100.000 | 50.000 | 25.000 | 16.667 | 10.000 |
| 60.000 | 120.000 | 60.000 | 30.000 | 20.000 | 12.000 |
| 75.000 | 150.000 | 75.000 | 37.500 | 25.000 | 15.000 |
| Time = Distance / Speed. Assumes constant speed along the path. 1 AU = 149,597,870.7 km ≈ 92,955,807.3 miles; 1 year = 365.25 days. | |||||
What is an Astronomical Unit?
An astronomical unit (AU) is a unit of length used in astronomy. It is defined as exactly 149,597,870,700 meters (149,597,870.7 kilometers), which is close to the Earth’s average distance from the Sun. The AU is commonly used to express distances within our solar system and to compare the relative distances of planets and other celestial objects from the Sun.
How to Calculate Average Orbital Speed?
The following steps outline how to calculate the average orbital speed for an approximately circular orbit.
- First, determine the semi-major axis (or orbital radius) a in astronomical units (AU).
- Next, determine the orbital period T in years.
- For a near-circular orbit, compute the distance traveled in one orbit as D ≈ 2πa (in AU).
- Finally, compute the average orbital speed using v = D / T (equivalently v ≈ 2πa/T).
Example Problem :
Use the following variables as an example problem to test your knowledge. For a near-circular orbit, v ≈ 2πa/T = 2π(1)/1 ≈ 6.283 AU/year (≈ 29.8 km/s).
Semi-major axis (a) = 1 AU
Orbital Period (Years) = 1