| Detail: more less | |||||||
| Quantity | Symbol | Value in cgs units | Value in SI units | Uncertainty | |||
| astronomical unit | AU | 1.49597870700E+13 | cm | 1.49597870700E+11 | m | exact | |
| atomic mass unit, m(12C)/12 | u | 1.66053906660E-24 | gm | 1.66053906660E-27 | kg | 5.00E-37 | kg |
| Avogadro's number | NA | 6.02214076E+23 | mole-1 | ||||
| Boltzmann's constant | k | 1.380649E-16 | erg K-1 | 1.380649E-23 | J K-1 | exact | |
| day | day | 8.6400E+04 | s | exact | |||
| day, sidereal | 8.61640905E+04 | s | in 2009 | ||||
| electron mass | me | 9.1093837015E-28 | gm | 9.1093837015E-31 | kg | 2.80E-40 | kg |
| elementary charge | qe | 4.803204270E-10 | esu | 1.602176634E-19 | C | exact | |
| fine-structure constant | α | 7.2973525693E-03 | 1.10E-12 | ||||
| 1/α | 137.035999084 | 2.10E-08 | |||||
| hydrogen atomic mass (in populations) | mH | 1.007825 | u | ||||
| hydrogen molecular mass (in populations) | mH2 | 2.015650 | u | ||||
| light year | ly | 9.46052818E+17 | cm | 9.46052818E+15 | in 2000 | ||
| neutron mass | mn | 1.67492749804E-24 | gm | 1.67492749804E-27 | kg | 9.50E-37 | kg |
| 1.00866491595 | u | 4.90E-10 | u | ||||
| Newton's constant of gravitation | G | 6.67430E-08 | cm3 gm-1 s-2 | 6.67430E-11 | m3 kg-1 s-2 | 1.50E-15 | m3 kg-1 s-2 |
| parsec | pc | 1.37667319634E-02 | cm | 1.37667319634E-05 | m | exact, truncated | |
| Planck's constant | h | 6.62607015E-27 | erg s | 6.62607015E-34 | J Hz-1 | exact | |
| ħ = h/2π | 1.05457182E-27 | erg s | 1.05457182E-34 | J Hz-1 | exact, truncated | ||
| proton mass | mp | 1.67262192369E-24 | gm | 1.67262192369E-27 | kg | 5.10E-37 | kg |
| 1.007276466621 | u | 5.30E-11 | u | ||||
| solar irradiance at Earth | fÅ | 1.361E+06 | erg s-1 cm-2 | 1361 | W m-2 | variable | |
| solar luminosity | Le | 3.828E+33 | erg s-1 | 3.828E+26 | W | variable | |
| solar mass | Me | 1.98841E+33 | gm | 1.98841E+30 | kg | 7.00E+25 | kg |
| solar mass parameter | GMe | 1.327124421E+26 | dyne cm2 | 1.327124421E+20 | N m2 | 1.00E+12 | N m2 |
| solar photospheric radius | Re | 6.9566E+10 | cm | 6.9566E+08 | m | 1.40E+05 | m |
| solar photospheric effective temperature | Tee | 5771 | K | = (Le/4πσRe2)1/4 | |||
| speed of light in vacuum | c | 2.99792458E+10 | cm s-1 | 2.99792458E+08 | m s-1 | exact | |
| standard acceleration of gravity | g | 9.80665E+02 | cm s-2 | 9.80665 | m s-2 | exact | |
| standard atmospheric pressure | atm | 1.01325E+06 | dyne cm-2 | 1.01325E+05 | N m-2 | exact | |
| Stefan-Boltzmann constant | σ | 5.670374419E-05 | erg s-1 cm-2 K-4 | 5.670374419E-08 | W m-2 K-4 | exact; truncated | |
| vacuum electric permittivity | ε0 | --- | 8.8541878128E-12 | farad m-1 | 1.30E-21 | farad m-1 | |
| vacuum magnetic permeability | μ0 | --- | 1.25663706212E-06 | N amp-2 | 1.90E-16 | N amp-2 | |
| year, sidereal | 3.1558150E+07 | s | in 2000 | ||||
| year, tropical | yr | 3.1556925E+07 | s | in 2000 | |||
| Sources: | |||||||
| US National Institute of Standards and Technology | http://physics.nist.gov/constants | ||||||
| US Naval Observatory | https://aa.usno.navy.mil/downloads/publications/Constants_2021.pdf | ||||||