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31.5: Some Useful Constants for Astronomy (Appendix E)

  • Page ID
    19716
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    Table \(\PageIndex{1}\): Physical Constants
    Name Value
    speed of light (c) 2.9979 × 108 m/s
    gravitational constant (G) 6.674 × 10−11 m3/(kg s2)
    Planck’s constant (h) 6.626 × 10−34 J-s
    mass of a hydrogen atom (MH) 1.673 × 10−27 kg
    mass of an electron (Me) 9.109 × 10−31 kg
    Rydberg constant (R) 1.0974 × 107 m−1
    Stefan-Boltzmann constant (σ) 5.670 × 10−8 J/(s·m2 deg4)1
    Wien’s law constant (λmaxT) 2.898 × 10−3 m K
    electron volt (energy) (eV) 1.602 × 10−19 J
    energy equivalent of 1 ton TNT 4.2 × 109 J

     

    Table \(\PageIndex{2}\): Astronomical Constants
    Name Value
    astronomical unit (AU) 1.496 × 1011 m
    Light-year (ly) 9.461 × 1015 m
    parsec (pc) 3.086 × 1016 m = 3.262 light-years
    sidereal year (y) 3.156 × 107 s
    mass of Earth (MEarth) 5.974 × 1024 kg
    equatorial radius of Earth (REarth) 6.378 × 106 m
    obliquity of ecliptic 23.4° 26’
    surface gravity of Earth (g) 9.807 m/s2
    escape velocity of Earth (vEarth) 1.119 × 104 m/s
    mass of Sun (MSun) 1.989 × 1030 kg
    equatorial radius of Sun (RSun) 6.960 × 108 m
    luminosity of Sun (LSun) 3.85 × 1026 W
    solar constant (flux of energy received at Earth) (S) 1.368 × 103 W/m2
    Hubble constant (H0) approximately 20 km/s per million light-years, or approximately 70 km/s per megaparsec

    Footnotes

    1deg stands for degrees Celsius or kelvins