The Planets
by Dominic Ford, Editor
Last updated: 4 Dec 2019
Physical characteristics of the planets
| Planet | Mass (Earth masses) | Radius (Earth radii) | Mean distance from Sun (AU) | Orbital period |
| Mercury | 0.055 | 0.3829 | 0.387 | 88 days |
| Venus | 0.815 | 0.950 | 0.723 | 225 days |
| Earth | 1 | 1 | 1 | 365.2564 days |
| Mars | 0.107 | 0.532 | 1.524 | 687 days |
| Jupiter | 317.8 | 10.96 | 5.204 | 11.862 yrs |
| Saturn | 95.152 | 9.4492 | 9.582 | 29.46 yrs |
| Uranus | 14.54 | 4.01 | 19.23 | 84.3 yrs |
| Neptune | 17.147 | 3.883 | 30.10 | 164.8 yrs |
Orbital elements of the planets
Below are osculating elements for the planets, given for epoch 2000 January 1.5 (i.e. Julian Day 2451545.0).
The elements are a least-squares fit to the 250-year span of the DE 200 planetary ephemeris to a Keplerian orbit, where each element is allowed to vary linearly with time. The resulting elements fit the positions of the terrestrial planets to within 25 arcseconds or better, but achieves only 10-arcminute accuracy for Saturn. Elements are referenced to mean ecliptic and equinox of J2000 at the J2000 epoch (2451545.0 JD).
| Planet | Semimajor axis (AU) |
Eccentricity | Inclination degrees |
Longitude of Ascending Node degrees |
Argument of perihelion degrees |
Mean anomaly at epoch degrees |
| Mercury | 0.38709893 | 0.20563069 | 7.00487 | 48.33167 | 29.12478 | 174.79439 |
| Venus | 0.72333199 | 0.00677323 | 3.39471 | 76.68069 | 54.85229 | 50.44675 |
| Mars | 1.52366231 | 0.09341233 | 1.85061 | 49.57854 | 286.46230 | 19.41248 |
| Jupiter | 5.20336301 | 0.04839266 | 1.30530 | 100.55615 | -85.80230 | 19.65053 |
| Saturn | 9.53707032 | 0.05415060 | 2.48446 | 113.71504 | -21.28310 | -42.48762 |
| Uranus | 19.19126393 | 0.04716771 | 0.76986 | 74.22988 | 96.73436 | 142.26794 |
| Neptune | 30.06896348 | 0.00858587 | 1.76917 | 131.72169 | -86.75034 | 259.90868 |
Derivatives of the orbital elements of the planets
| Planet | Semimajor axis AU/Cyr |
Eccentricity /Cyr |
Inclination deg/Cyr |
Longitude of Ascending Node deg/Cyr |
Argument of perihelion deg/Cyr |
Mean anomaly deg/Cyr |
| Mercury | 0.00000066 | 0.00002527 | -0.00653 | -0.12397 | 0.28330 | 149472.51520 |
| Venus | 0.00000092 | -0.00004938 | -0.00079 | -0.27691 | 0.24669 | 58517.84579 |
| Mars | -0.00007221 | 0.00011902 | -0.00707 | -0.28339 | 0.71694 | 19139.87306 |
| Jupiter | 0.00060737 | -0.00012880 | -0.00115 | 0.33810 | -0.10479 | 3034.51067 |
| Saturn | -0.00301530 | -0.00036762 | 0.00170 | -0.44196 | -0.09940 | 1223.05607 |
| Uranus | 0.00152025 | -0.00019150 | -0.00058 | -0.46706 | 0.83166 | 428.12090 |
| Neptune | -0.00125196 | 0.00002510 | -0.00101 | -0.04201 | -0.19255 | 218.69268 |
Cyr = 1 Julian century (i.e. 36525 days)
References
Explanatory Supplement to the Astronomical Almanac. 1992. K. P. Seidelmann, Ed., p.316 (Table 5.8.1), University Science Books, Mill Valley, California.