Summary of Constants

Physical Constants

(ref. Physics Today, Aug. 1995 pg. BG9)

AU = astronomical unit = 1.4960 · 10¹³ cm
c = speed of light = 2.99792458 · 10¹⁰ cm/s
G = 6.67259(85) · 10^-8 dyne cm²/gm²
h = Planck's constant = 6.626075(40) · 10^-27 erg sec
k = Boltzmann's constant = 1.380658(12) · 10^-16 erg/K
N_a = Avogadro's number = 6.0221367(36) · 10²³ /mole
= Stefan-Boltzmann constant = 5.67051(19) · 10^-5 erg/s/cm²/K⁴
S₀ = 1.37 · 10⁶ erg/cm²
R_univ = N_a · k = 8.3143 · 10⁷ erg/mole/K
<mw>_H2O = 18.016 gm/mole
<mw>_O3 = 47.9982 gm/mole

Earth Constants

R_eq = 6378.388 km
M = 5.975 · 10²⁷ gm
<mw>_{dry air} = 28.964 gm/mole
R_g = 0.28705 · 10⁷ erg/gm/K
N₀ = Loschmidt's number = 2.686763(23) · 10¹⁹ molecules/cm³
g_s = Standard surface gravity = 980.665 cm/s
P_s = Standard surface pressure = 1.01325 · 10⁶ dyne/cm²
c_p = 1.006 · 10⁷ erg/gm/K at stp
c_v = 0.718 · 10⁷ erg/gm/K at stp
= c_p/c_v = 1.401 at stp

Unit Conversion

1 knot = 1 nautical mile/hour = 1.151555 mile/hour = 1.853248 Km/hr
1 megaton = 4.2 · 10²² erg = 4.2 · 10¹⁵ Joule
1 AU = 1.495 · 10⁸ Km = 8.31 light minutes