Physical & Astronomical constants, in cgs units

 

Physical constants

Quantity
Symbol
Value (cgs units)
Value (eV units)
speed of light (in vacuum)
c
2.99792458 × 1010 cm s-1
Newton’s gravitational constant
G
6.6743 × 10-8 cm3 g-1 s-2
Planck’s constant
h
6.6261 × 10-27 cm2 g s-1
4.1357 × 10-15 eV s
reduced Planck’s constant
ℏ = h/2π
1.0546 × 10-27 cm2 g s-1
6.5821 × 10-16 eV s
Boltzmann’s constant
k
1.3807 × 10-16 cm2 g s-2 K-1
8.6173 × 10-5 eV K-1
Stefan-Boltzmann constant
σ
5.6704 × 10-5 g s-3 K-4
electron charge
e
4.8032 × 10-10 cm3/2 g1/2 s-1
electron mass
me
9.1094 × 10-28 g
0.511 MeV/c2
proton mass
mp
1.6726× 10-24 g
938.272 MeV/c2
neutron mass
mn
1.6749× 10-24 g
939.563 MeV/c2
atomic mass unit
u
1.6605 × 10-24 g
931.494 MeV/c2
erg (unit of energy)
erg
1 cm2 g s-2
6.2415 × 1011 eV

Astronomical constants

Quantity
Symbol
Value (cgs units)
Solar mass
M☉
1.989 × 1033 g
Earth mass
M⊕
5.974 × 1027 g
Jupiter mass
MJ
1.899 × 1030 g
Solar radius
R☉
6.957 × 1010 cm
Earth radius
R⊕
6.378 × 108 cm
Jupiter radius
RJ
7.149 × 109 cm
Solar luminosity
L☉
3.839 × 1033 erg s-1
astronomical unit
AU
1.496 × 1013 cm
parsec
pc
3.086 × 1018 cm
light-year
ly
9.461 × 1017 cm
year
yr
3.156 × 107 s

An additional list of useful constants:

Length:

  • 1 inch = 2.54 cm
  • 1 mile = 1.6 km
  • 1 km = 1000 m
  • 1 m = 100 cm = 1000 mm = 109 nm
  • Planck Legnth = 1.616252×10-35 m = sqrt (hbar G/c3)
  • Classical Electron Radius = 2.81794×10-15 m = e2/ me c2
  • Proton Radius = 0.83×10-15 m = 0.83 femtometer = 0.83×10-13 cm
  • 1 Angstrom = 10-10 m = 10-8 cm
  • 1 Earth Radius = 6.37814×108 cm = 6.37814×106 m (Equatorial)
  • 1 Jupiter Radius = 7.1492×109 cm = 7.1492×107 m (Equatorial)
  • 1 Solar Radius = 6.957 × 1010 cm = 6.957 × 108 m (Equatorial)
  • 1 Moon’s Mean Orbital Radius = 384,400 km = 3.8440×108 m
  • 1 AU = 1.4960×1011 m = 1.4960×108 km (Astronomical Unit)
  • 1 ly = 9.4605×1015 m = 9.4605×1012 km (light year)
  • 1 pc = 3.0857×1016 m = 3.0857×1013 km = 3.261633 ly = 206264.806 AU (parsec) = 3.0857×1018 cm
  • 1 Mpc = 106 pc (Megaparsec) = 3.0857×1024 cm
  • DH = c/H0 = 3000 h-1 Mpc = 9.26×1027 h-1 cm (The Hubble Scale)

Angles:

  • 1° = 1 degree = 60′ = 60 arcminutes
  • 1′ = 60″ = 60 arcseconds
  • 1 radian = 360°
    /2 pi = 57.2957795131° = 206264.806″
  • Area of a Sphere = 41252.96124 square degrees = 4 pi Steradians

Mass:

  • 1 amu = 1.6605402 x10-24 gram = 1.6605402 x10-27 kg
  • 1 amu c2 = 931.49432 MeV
  • 1 Hydrogen Atom Mass = 1.007825 amu = 1.673534 x10-24 gram
  • 1 Helium 4 Atom Mass = 4.00260325415 amu
  • 1 Carbon 12 Atom Mass = 12.0000000 amu
  • 1 Proton Mass = 1.6726231 x10-24 gram
  • 1 Neutron Mass = 1.674920 x10-24 gram
  • 1 Electron Mass = 9.1093897 x10-28 gram
  • 1 kg = 2.20462 lb
  • 1 Solar Mass = 1.989×1033 gram = 1.989×1030 kg
  • 1 Jupiter Mass = 1.899×1030 gram = 1.899×1027 kg
  • 1 Earth Mass = 5.9736×1027 gram = 5.9736×1024 kg
  • 1 Lunar Mass = 7.3477×1025 gram = 7.3477×1022 kg
  • (Proton Mass)/(Electron Mass) = 1836.15
  • Earth’s Mean Density = 5515.3 kg/m3
  • Moon’s Mean Density = 3346.4 kg/m3

Time:

  • 1 Planck Time = 5.39124×10-44 s = sqrt (hbar G/c5)
  • 1 Sidereal Day = 23h 56m 04.09054s
  • 1 Solar Day = 24h = 86400 s
  • 1 Sidereal Year = 3.155815×107 s
  • 1 Tropical Year = 3.155693×107 s

Energy:

  • 1 Joule = 2.39×10-1 calorie
  • 1 Joule = 107 ergs
  • 1 eV = 1.602177×10-12 erg = 1.602177×10-19 Joule
  • 1 Solar Luminosity = 3.826×1033 ergs/s = 3.826×1026 Joules/s = 3.826×1026 Watts
  • Sun’s Absolute Magnitude V = 4.83, B = 5.48, K = 3.28
  • Vega’s Absolute Magnitude V = 0.58, B = 0.58, K = 0.58

Temperature:

  • Solar Surface Effective Temperature = 5770 K

Physical Constants:

  • Avogadro’s Number = NA = 6.0221367×1023 /mole
  • Gravitational Constant = G = 6.67259×10-8 cm3 gram-1 s-2
    = 4.301×10-9 km2 Mpc MSun-1 s-2
  • Planck’s Constant = h = 6.6260755×10-27 erg s
  • Speed of Light = c = 2.99792458×1010 cm s-1 = 2.99792458×108 m s-1
  • Boltzmann’s Constant = k = 1.380658×10-16 erg K-1
  • Stefan-Boltzmann Constant = &sigma = 5.67051×10-5 erg cm-2 K-4 s-1
  • Radiation Density Constant = a = 7.56591×10-15 erg cm-3 K-4
  • Rydberg = RH = 1.09677585×10 5 cm-1
  • Electron charge = e = 4.8032×10-10 esu = 1.6022×10-19 Coulomb
  • 1 Coulomb = 6.24151×1018 e