16.5: Some Useful Constants for Astronomy (Appendix E)
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| Table \(\PageIndex{1}\): Physical Constants | |
|---|---|
| Name | Value |
| speed of light ( c ) | 2.9979 × 10 8 m/s |
| gravitational constant ( G ) | 6.674 × 10 −11 m 3 /(kg s 2 ) |
| Planck’s constant ( h ) | 6.626 × 10 −34 J-s |
| mass of a hydrogen atom ( M H ) | 1.673 × 10 −27 kg |
| mass of an electron ( M e ) | 9.109 × 10 −31 kg |
| Rydberg constant (R ∞ ) | 1.0974 × 10 7 m −1 |
| Stefan-Boltzmann constant (σ) | 5.670 × 10 −8 J/(s·m 2 deg 4 ) 1 |
| Wien’s law constant (λ max T) | 2.898 × 10 −3 m K |
| electron volt (energy) (eV) | 1.602 × 10 −19 J |
| energy equivalent of 1 ton TNT | 4.2 × 10 9 J |
| Table \(\PageIndex{2}\): Astronomical Constants | |
|---|---|
| Name | Value |
| astronomical unit (AU) | 1.496 × 10 11 m |
| Light-year (ly) | 9.461 × 10 15 m |
| parsec (pc) | 3.086 × 10 16 m = 3.262 light-years |
| sidereal year (y) | 3.156 × 10 7 s |
| mass of Earth ( M Earth ) | 5.974 × 10 24 kg |
| equatorial radius of Earth ( R Earth ) | 6.378 × 10 6 m |
| obliquity of ecliptic | 23° 26’ |
| surface gravity of Earth ( g ) | 9.807 m/s 2 |
| escape velocity of Earth ( v Earth ) | 1.119 × 10 4 m/s |
| mass of Sun ( M Sun ) | 1.989 × 10 30 kg |
| equatorial radius of Sun ( R Sun ) | 6.960 × 10 8 m |
| luminosity of Sun ( L Sun ) | 3.85 × 10 26 W |
| solar constant (flux of energy received at Earth) (S) | 1.368 × 10 3 W/m 2 |
| Hubble constant (H 0 ) | approximately 20 km/s per million light-years, or approximately 70 km/s per megaparsec |
Footnotes
1 deg stands for degrees Celsius or kelvins