Physical Constants and Astronomical Data

Physical Constants

(converted to CGS units from the NIST Constant Index)
Name Symbol Number Exp CGS Units Relative Error
(ppm)
speed of light in a vacuum c 2.99792458 10  cm s-1 exact
Planck constant h 6.6260755(40) -27  erg s 0.60
hbar 1.05457266(63) -27  erg s 0.60
Gravitational constant G 6.67259(85) -8  cm3 g-1 s-2 128
Electron charge e 4.8032068(14) -10  esu 0.30
Mass of electron me 9.1093897(54) -28  g 0.59
Mass of proton mp 1.6726231(10) -24  g 0.59
Mass of neutron mn 1.6749286(10) -24  g 0.59
Mass of hydrogen mH 1.6733 -24  g --
Atomic mass unit amu 1.6605402(10) -24  g 0.59
Avagadro's number NA 6.0221367(36) 23 0.59
Boltzmann constant k 1.380658(12) -16  erg k-1 8.5
Electron volt eV 1.6021772(50) -12  erg ~0.60
Radiation density constant a 7.5646 -15  erg cm-3 K-4 --
Stefan-Boltzmann constant \sigma 5.67051(19) -5  erg cm-2 K-4 s-1 34
Fine structure constant \alpha 7.29735308(33) -3 0.045
Rydberg constant R\inf 2.1798741(13) -11  erg 0.60

Note: a "--" in the error column means that I have not found a good source for that constant, so the value quoted is just an approximation

Astronomical Units/Data 

NAME                    SYMBOL  NUMBER  EXP     CGS UNITS
----------------------------------------------------------------
Astronomical unit	AU	1.496	13	cm
Parsec			pc	3.086	18	cm
Light year		ly	9.463	17	cm
Solar mass		Mo	1.99	33	g
Solar radius		Ro	6.96	10	cm
Solar luminosity	Lo	3.9	33	erg s-1
Solar Temperature	To	5.780	3	K
----------------------------------------------------------------

NAME	MASS (g)  RADIUS (cm) PERIOD (yr) SEMI-MAJOR (AU) ECCENTRICITY
----------------------------------------------------------------------
Mercury	3.303 26  2.439  8    2.4085  -1  3.87096  -1     0.205622
Venus	4.870 27  6.050  8    6.1521  -1  7.23342  -1     0.006783
Earth	5.976 27  6.378  8    1.00004  0  9.99987  -1     0.016684
Mars	6.418 26  3.397  8    1.88089  0  1.523705  0     0.093404
Jupiter	1.899 30  7.140  9    1.18622  1  5.204529  0     0.047826
Saturn	5.686 29  6.000  9    2.94577  1  9.575133  0     0.052754
Uranus	8.66  28  2.615  9    8.40139  1  1.930375  1     0.050363
Neptune	1.030 29  2.43   9    1.64793  2  3.020652  1     0.004014
Pluto	1.    25  1.2    8    2.47686  2  3.991136  1     0.256695
----------------------------------------------------------------------

A Few Conversion Factors

CGS --> SI Multiply by
centimeter (cm) meter (m) 10-2
gram (g) kilogram (kg) 10-3
erg Joule (J) 10-7
dyne (dyn) newton (N) 10-5

Other Information Sources

Last updated:5/14/96
Written by Chris Dolan (http://www.astro.wisc.edu/~dolan/)