Astronomical unit per year (AU/yr) is a unit of velocity used in astronomy to denote the orbital motion of planets, asteroids, and close binaries around the star. This unit shall be useful especially for planets because units in this derivative are based on our homeworld in unity. Another reason is that this unit is calculated most simply, easier than calculating orbital velocity in km/s, mi/s, kph or mph.
1 AU/yr is the orbital velocity of Earth divided by 2π, 4.756 km/s or 2.955 mi/s (17120 kph or 10640 mph), about the velocity of Pluto. To calculate the orbital velocity, simply divide semimajor axis in astronomical units by orbital period in years and then multiply the quotient 2π.
Object | Semimajor axis | Period | Velocity |
---|---|---|---|
2M1207b | 40.641 AU | 1623.866 yr | 0.153 AU/yr |
Sedna | 518.568 AU | 11398.250 yr | 0.286 AU/yr |
Eris | 68.009 AU | 560.900 yr | 0.762 AU/yr |
Fomalhaut b | 113.516 AU | 872.152 yr | 0.816 AU/yr |
Pluto | 39.264 AU | 247.681 yr | 0.996 AU/yr |
Neptune | 30.058 AU | 164.791 yr | 1.146 AU/yr |
Uranus | 19.229 AU | 84.323 yr | 1.432 AU/yr |
PSR B1620-26 b | 23.251 AU | 96.413 yr | 1.514 AU/yr |
Saturn | 9.538 AU | 29.457 yr | 2.033 AU/yr |
Jupiter | 5.200 AU | 11.859 yr | 2.754 AU/yr |
Ceres | 2.765 AU | 4.601 yr | 3.778 AU/yr |
Mars | 1.524 AU | 1.881 yr | 5.082 AU/yr |
Earth | 1.000 AU | 1.000 yr | 6.283 AU/yr |
Venus | 0.723 AU | 0.615 yr | 7.388 AU/yr |
Mercury | 0.387 AU | 0.241 yr | 10.020 AU/yr |
Proxima Centauri b | 0.050 AU | 0.031 yr | 10.324 AU/yr |
51 Pegasi b | 0.053 AU | 0.012 yr | 28.757 AU/yr |
PSR J1719-1438 b | 4.452E-3 AU | 2.4834E-4 yr | 112.627 AU/yr |