910 Encyclopedia of the Solar System
TABLE 2 Selected Astronomical Constants
Astronomical unit, AU 1.4959787066× 1011 meters
Speed of light, c 2.99792458× 108 meters second−^1
AU in light time 499.00478353 seconds
Gaussian gravitational constant 0.01720209895 AU^3 /^2 day−^1 solar mass−^1 /^2
Gravitational constant, G 6.67259× 10 −^11 meters^3 kg−^1 sec−^2
Mass of the Sun 1.9891× 1030 kilograms
Mass of the Earth 5.9742× 1024 kilograms
Solar constant 1368 watts meter−^2
Sun-Jupiter mass ratio 1047.3486
Earth-Moon mass ratio 81.30059
Equatorial radius of the Earth 6378.136 kilometers
Obliquity of the ecliptic (J2000) 23 ◦26’ 21.412”
Earth sidereal day 23 hours 56 minutes 4.09054 seconds
Sidereal year 365.25636 days
Semimajor axis of the Earth’s orbit 1.00000105726665 AU
Parsec, pc 206,264.806 AU
Age of the solar system 4.56× 109 years
Age of the galaxy 13 × 109 years
