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Astrodynamic Parameters
This page contains selected parameters commonly used in astrodynamic computations. References are listed below.
| Parameter | Symbol | Value | Reference |
|---|---|---|---|
| day | d | 86400 s | |
| Julian year | y | 365.25 d | 1. (see below) |
| Julian century | Cy | 36525 d | 1. (see below) |
| speed of light in vacuum | c | 299792458 m/s | 2018 CODATA recommended values |
| astronomical unit | au | 149597870700 m | IAU 2012 Resolution B1 |
| mean sidereal day | 86164.09054 s [ 23:56:04.09054 ] | 1. (see below) | |
| sidereal year (quasar ref. frame) | 365.25636 d | ||
| Newtonian constant of gravitation | G | 6.67430 (± 0.00015) x 10-11 kg-1 m3 s-2 | 2018 CODATA recommended values |
| general precession in longitude | 5028.83 (± 0.04) arcsec/Cy | ||
| obliquity of ecliptic (J2000) | ε | 84381.412 (± 0.005) arcsec | 2. (see below) |
| obliquity of ecliptic (J2000) [IAU 1976] | ε | 84381.448 arcsec | 3. (see below) |
| light time for 1 au | ΤA | au/c = 499.004783836 s | |
| heliocentric gravitational constant | GMsun | 1.32712440041279419 x 1020 m3 s-2 | 4. (see below) |
Planetary Masses
These data are from the JPL planetary ephemeris DE440 (ref. 4, below).
| Planet | GM (km3 s-2) |
|---|---|
| Mercury | 22031.868551 |
| Venus | 324858.592000 |
| Earth | 398600.435507 |
| Moon | 4902.800118 |
| Mars system | 42828.375816 |
| Jupiter system | 126712764.100000 |
| Saturn system | 37940584.841800 |
| Uranus system | 5794556.400000 |
| Neptune system | 6836527.100580 |
| Pluto system | 975.500000 |
Notes
- The dwarf planet Pluto is included in the list of planetary system masses above because it is included in JPL’s planetary ephemeris for historical reasons.
- Data are from the 1994 IAU file of current best estimates unless otherwise noted.
- JPL asteroid and comet ecliptic orbital elements are based on the adopted IAU 1976 constant for the obliquity of the ecliptic.
References
-
Seidelmann, P. K. (Ed.), 1992, “Explanatory supplement to the Astronomical Almanac”, University Science Books
-
Standish, E.M., 1995, “Report of the IAU WGAS Sub-Group on Numerical Standards”, in Highlights of Astronomy (I. Appenzeller, ed.), Table 1, Kluwer Academic Publishers, Dordrecht.
-
Lederle, T, 1980, “The IAU (1976) System of Astronomical Constants”, Astronomische Gesellschaft…, 48:59:65.
-
Park, R.S., et al., 2021, “The JPL Planetary and Lunar Ephemerides DE440 and DE441”, Astronomical Journal, 161:105.