Astrodynamic Constants and Parameters


Table 1. Defining Constants
Julian day   d = 86400 s
Julian year   yr = 365.25 d
Julian Century   Cy = 36525 d
Speed of light   c = 299792458 m/s
Gaussian gravitational constant     k = 0.01720209895 (AU3/d2)˝

Table 2. Primary Constants
Mean sidereal day       86164.09054 s = 23:56:04.09054
Sidereal year (quasar ref. frame)       365.25636 d
Light time for 1 AU    tauA = 499.004783806 (± 0.00000001) s
Gravitational constant    G = 6.67259 (± 0.00030) x 10-11 kg-1 m3 s-2 
General precession in longitude        5028.83 (± 0.04) arcsec/Cy
Obliquity of ecliptic (J2000)    epsilon = 84381.412 (± 0.005) arcsec
Mass: Sun / Mercury       6023600. (± 250.)
Mass: Sun / Venus       408523.71 (± 0.06)
Mass: Sun / (Earth+Moon)       328900.56 (± 0.02)
Mass: Sun / (Mars system)       3098708. (± 9.)
Mass: Sun / (Jupiter system)       1047.3486 (± 0.0008)
Mass: Sun / (Saturn system)       3497.898 (± 0.018)
Mass: Sun / (Uranus system)       22902.98 (± 0.03)
Mass: Sun / (Neptune system)       19412.24 (± 0.04)
Mass: Sun / (Pluto system)       1.35 (± 0.07) x 108
Mass: Moon / Earth       0.012300034 (± 3 x 10-9)

Table 3. Derived Constants
Astronomical unit distance     c * tauA = AU = 1.49597870691 x 1011 (± 3) m 
Heliocentric gravitational constant    k2 AU3 d-2 = GMsun = 1.32712440018 x 1020 (± 8 x 109) m3 s-2 
Mass: Earth / Moon       81.30059 (± 0.00001)


Notes: Data are from the 1994 IAU file of current best estimates. Planetary ranging determines the Earth/Moon mass ratio. The value for 1 AU is taken from JPL's current planetary ephemeris DE-405.

Reference:

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.


JPL/SSD Home Credits/Awards

Contact: Webmaster (webmaster@ssd.jpl.nasa.gov)

Last modified: 2001 August 6 15:51