Physical & Astronomical Constants

Here is a 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 = 1.616252x10-35 m = sqrt (hbar G/c3)
Classical Electron Radius = 2.81794x10-15 m = e2/ me c2
Proton Radius = 0.83x10-15 m = 0.83 femtometer = 0.83x10-13 cm
1 Angstrom = 10-10 m = 10-8 cm
1 Earth Radius = 6.37814x108 cm = 6.37814x106 m (Equatorial)
1 Jupiter Radius = 7.1492x109 cm = 7.1492x107 m (Equatorial)
1 Solar Radius = 6.959910 cm = 6.9599x108 m (Equatorial)
1 Moon's Mean Orbital Radius = 384,400 km = 3.8440x108 m
1 AU = 1.4960x1011 m = 1.4960x108 km (Astronomical Unit)
1 ly = 9.4605x1015 m = 9.4605x1012 km (light year)

1 pc = 3.0857x1016 m = 3.0857x1013 km = 3.261633 ly = 206264.806 AU (parsec) = 3.0857x1018 cm

1 Mpc = 106 pc (Megaparsec) = 3.0857x1024 cm

DH = c/H0 = 3000 h-1 Mpc = 9.26x1027 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 = 1.989x1033 gram = 1.989x1030 kg
1 Jupiter Mass = 1.899x1030 gram = 1.899x1027 kg
1 Earth Mass = 5.9736x1027 gram = 5.9736x1024 kg
1 Lunar Mass = 7.3477x1025 gram = 7.3477x1022 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 = 5.39124x10-44 s = sqrt (hbar G/c5)
1 Sidereal Day = 23h 56m 04.09054s
1 Solar Day = 24h = 86400 s
1 Sidereal Year = 3.155815x107 s
1 Tropical Year = 3.155693x107 s

Energy:

1 Joule = 2.39x10-1 calorie
1 Joule = 107 ergs
1 eV = 1.602177x10-12 erg = 1.602177x10-19 Joule
1 Solar Luminosity = 3.826x1033 ergs/s = 3.826x1026 Joules/s = 3.826x1026 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 = 6.0221367x1023 /mole
Gravitational Constant = G = 6.67259x10-8 cm3 gram-1 s-2 = 4.301x10-9 km2 Mpc MSun-1 s-2
Planck's Constant = h = 6.6260755x10-27 erg s
Speed of Light = c = 2.99792458x1010 cm s-1 = 2.99792458x108 m s-1
Boltzmann's Constant = k = 1.380658x10-16 erg K-1
Stefan-Boltzmann Constant = &sigma = 5.67051x10-5 erg cm-2 K-4 s-1
Radiation Density Constant = a = 7.56591x10-15 erg cm-3 K-4
Rydberg = RH = 1.09677585x10 5 cm-1
Electron charge = e = 4.8032x10-10 esu = 1.6022x10-19 Coulomb
1 Coulomb = 6.24151x1018 e


courtesy of cfa.harvard.edu.