VALUES USED FOR ASTRONOMICAL CONSTANTS BY George Gladfelter
May 13, 2020
Astronomical Unit 149597870.7 km IAU definition of the A.U.
Radius of Sun 696000 km see AA2020,JPL/Horizons
Radius Solar photosphere 696300 km but see AA2020
Volumetric Solar radius 695700 km see AA2019 and before
Solar Mass 1.98855e30 kg
Solar Radiated Power 3.846e26 Watts
Solar Power at 1 A.U. 1367.6 Watts per sq. meter
Solar Color Temperature 5778 K
Earth equatorial radius 6378.1366 km (WGS84)
Earth flattening (1/F) 298.25642 see AA2019
Earth Polar semi-axis 6356.75186 km derived from flattening
Earth center to surface at 45 degrees geographic latitude (WGS84):
6367.4532 km (derived)
Earth Radius factor for including atmosphere: 1.015 (ad hoc)
Lunar Mean Radius 1734.4 km (+/- 0.1) AA2020 but not IAU
Lunar Equatorial Radius 1738.1 km NASA 2016
Lunar Polar Radius 1736.0 km
Mean sidereal days per UT1 day 1.00273781191135448
Speed of Light 299792.458 km/sec (defines the meter)
Kilometers per mile 1.609344 (exact in decimal notation, defines the mile)
Julian Day for 2000-JAN-01 12hours TT 2451545.0
Julian Day (UTC) for inception of UTC 2441317.5
Julian Day (TT) at inception of UTC 2441317.5004882407
Julian Day (UT) for UNIX time = 0 seconds 2440587.5
AA = Astronomical Almanac, IAU = International Astronomical Union
The constants listed above are generally used in all programs and functions unless there might be a specific reason for using a variant.
Other constants that are used only in one particular function or application are not listed here.