249 Some Useful Constants for Astronomy
| Physical Constants | |
|---|---|
| Name | Value |
| speed of light (c) | 2.9979 × 108 m/s |
| gravitational constant (G) | 6.674 × 10−11 m3/(kg s2) |
| Planck’s constant (h) | 6.626 × 10−34 J-s |
| mass of a hydrogen atom (MH) | 1.673 × 10−27 kg |
| mass of an electron (Me) | 9.109 × 10−31 kg |
| Rydberg constant ( ) | 1.0974 × 107 m−1 |
| Stefan-Boltzmann constant (σ) | 5.670 × 10−8 J/(s·m2 deg4)[1] |
| Wien’s law constant (λmaxT) | 2.898 × 10−3 m K |
| electron volt (energy) (eV) | 1.602 × 10−19 J |
| energy equivalent of 1 ton TNT | 4.2 × 109 J |
| Astronomical Constants | |||
| Name | Value | ||
| astronomical unit (AU) | 1.496 × 1011 m | ||
| Light-year (ly) | 9.461 × 1015 m | ||
| parsec (pc) | 3.086 × 1016 m = 3.262 light-years | ||
| sidereal year (y) | 3.156 × 107 s | ||
| mass of Earth (REarth) | 5.974 × 1024 kg | ||
| equatorial radius of Earth | 6.378 × 106 m | ||
| obliquity of ecliptic | 23.4° 26’ | ||
| escape velocity of Earth (vEarth) | 1.119 × 104 m/s | ||
| mass of Sun (MSun) | 1.989 × 1030 kg | ||
| equatorial radius of Sun (RSun) | 6.960 × 108 m | ||
| luminosity of Sun (LSun) | 3.85 × 1026 W | ||
| solar constant (flux of energy received at Earth) (S) | 1.368 × 103 W/m2 | ||
| Hubble constant (H0) | approximately 20 km/s per million light-years, or approximately 70 km/s per megaparsec |