# Physical Constants (1998 CODATA Recommended Values)

 Speed of light* c = 299 792 458 m/sec (exactly) Constant of gravitation G = (6.673 ± 0.010) x 10-11 m3/kg · sec2 Planck’s constant h = (6.626 068 ± 0.000 0052) x 10-34 J · s Boltzmann’s constant k = (1.380 650 3 ± 0.000 002 4) x 10-23 J/K Stefan-Boltzmann constant s = (5.670 400 ± 0.000 040) x 10-8 W/m2 · K4 Wien displacement constant lmaxT = (2.897 768 6 ± 0.000 005) x 107 A = K Mass of neutron mn = (1.674 92716 ± 0.000 00013) x 10-27 kg Mass of proton mp = (1.672 621 58 ± 0.000000 13) x 10-27 kg Mass of electron me = (9.109 381 88 ± 0.000000 72) x 10-31 kg Rydberg constant R = (10 973 731.568 549 ± 0.000 083) m-1

See http://physics.nist.gov/constants

# Mathematical Constants (to 100 places just for fun)

 p = 3.141 592 653 589 793 238 462 643 383 279 502 884 197 169 399 375       105 820 974 944 592 307 816 406 286 208 998 628 034 825 342 117 067 …   e = 2.718 281 828 459 045 235 360 287 471 352 662 497 757 247 093 699       959 574 966 967 627 724 076 630 353 547 594 571 382 178 525 166 427 …

# Astronomical Constants

 Astronomical Unit* 1 A.U. = 1.495 978 70 x 1011 m Solar parallax* p = 8.794 148 arcsec Parsec 1 pc = 3.086 x 1016 m = 206 264.806 A.U. = 3.261 633 ly Light-year 1 ly = (9.460 530) x 1015 m = 6.324 x 104 A.U. Tropical year (1900)*-(equinox to equinox) = 365.242 198 78 ephemeris days Julian century* = 36 525 days Day* = 86 400 sec Sidereal year = 365.256 366 ephemeris days = (3.155 815) x 107 sec Mass of Sun* M = (1.989 1) x 1030 kg Radius of Sun* R = 696 000 km Luminosity of Sun L = 3.827 x 1026 J/sec Mass of Earth* ME = (5.974 2) x 1024 kg Equatorial radius of Earth* RE = 6 378.140 km Center of Earth to center of Moon (mean) = 384 403 km Radius of Moon* RM = 1 738 km Mass of Moon* MM = 7.35 x 1022 kg Solar constant S = 1 368 W/m2 Direction of galactic center (2000.0 precession) a = 17h45.6m d = -28°56˘

*Adopted as “IAU (1976) system of astronomical constants” at the General Assembly of the International Astronomical Union that year.

The meter was redefined in 1983 to be the distance traveled by light in a vacuum in 1/299,792,458 second.