Physical constants etc

Quantity Symbol Value Units
Astronomical constants
Earth mass $M_\oplus$ $5.980\times10^{24}$ kg (kilograms)
Earth radius $R_\oplus$ $6.378\times10^{6}$ m (metres)
Solar mass $M_\odot$ $1.989\times10^{30}$ kg
Solar radius $R_\odot$ $6.960\times10^{8}$ m
Solar luminosity $L_\odot$ $3.862\times10^{26}$ W (Watts)
Solar effective temperature $T_{eff\odot}$ $5770$ K (Kelvin)
Common conversions
1 Astronomical unit AU $1.496\times10^{11}$ m
1 Parsec pc $3.086\times10^{16}$ m
  $3.262$ light years
1 Jansky Jy $10^{-26}$ W m$^{-2}$ Hz$^{-1}$ (Hz is Hertz)
1 Gauss G $10^{-4}$ T (Tesla)
1 Erg erg $10^{-7}$ J (Joules)
1 Electron volt eV $1.602\times10^{-19}$ J
Physical constants
Speed of light $c$ $2.998\times10^8$ m s$^{-1}$
Permeability of free space $\mu_0$ $4\pi\times10^{-7}$ H m$^{-1}$ (H is Henrys)
Permittivity of free space $\epsilon_0$ $8.854\times10^{-12}$ F m$^{-1}$ (F is Farads)
Charge on electron $e$ $1.602\times10^{-19}$ C (Coulombs)
Planck's constant $h$ $6.626\times10^{-34}$ J s
Gravitational constant $G$ $6.673\times10^{-11}$ N m$^2$ kg$^{-2}$ (N is Newtons)
Atomic mass unit $u$ $1.660\times10^{-27}$ kg
Rest mass of electron $m_e$ $9.109\times10^{-31}$ kg
Rest mass of proton $m_p$ $1.673\times10^{-27}$ kg
Rest mass of neutron $m_n$ $1.675\times10^{-27}$ kg
Boltzmann's constant $k$ $1.381\times10^{-23}$ J K$^{-1}$
Avogadro's number $N_A$ $6.023\times10^{23}$ mol$^{-1}$ (per mole)
Universal gas constant $R$ $8.314$ J K$^{-1}$ mol$^{-1}$
Stefan-Boltzmann constant $\sigma$ $5.67\times10^{-8}$ W m$^{-2}$ K$^{-4}$
Radiation constant $a$ $7.56\times 10^{-16}$ J m$^{-3}$ K$^{-4}$
Bohr magneton $\mu_B$ $9.274\times10^{-24}$ A m$^2$ (A is Amps)
Nuclear magneton $\mu_N$ $5.051\times10^{-27}$ A m$^2$
Acceleration due to gravity $g$ $9.81$ m s$^{-2}$
Standard atmospheric pressure 1 atm $1.013\times10^{5}$ N m$^{-2}$ (Pascals)
Thomson cross section $\sigma_T$ $6.65\times10^{-29}$ m$^2$