| symbol | name | value | unit | |
|---|---|---|---|---|
| c | speed of light in a vacuum | 299,792,458 | m/s | |
| G | gravitational constant | 6.67384 | × 10−7 | N m2/kg2 |
| h | planck's constant | 6.62606957 4.135667516 | × 10−34 × 10−15 | J s eV s |
| hc | 1.98644521 1239.84193 | × 10−25 | J m eV nm | |
| ℏ | h/2π reduced planck's constant dirac's constant | 1.054571726 6.58211928 | × 10−34 × 10−16 | J s eV s |
| ε0 | electric constant permitivitty of free space vacuum permitivitty | 8.854187817 | × 10−12 | C2/N m2 |
| μ0 | magnetic constant permeability of free space vacuum permeability | 4π | × 10−7 | T m/A |
| e | elementary charge | 1.602176565 | × 10−19 | C |
| me | electron mass | 9.10938291 0.510998928 0.00054857990946 | × 10−31 | kg MeV u |
| mp | proton mass | 1.672621777 938.272046 1.00727646812 | × 10−27 | kg MeV u |
| mn | neutron mass | 1.674927351 939.565379 1.00866491600 | × 10−27 | kg MeV u |
| mu | atomic mass constant | 1.660538921 931.494061 1 | × 10−27 | kg MeV u |
| NA | avogadro's constant | 6.02214129 | × 1023 | 1/mol |
| k | boltzmann's constant | 1.3806488 | × 10−23 | J/K |
| R | gas constant | 8.3144621 | J/mol K | |
| σ | stefan-boltzmann constant | 5.670373 | × 10−8 | W/m2K4 |
| b | wien displacement constant | 2.8977721 58.789254 | mm/K GHz/K | |
| g | standard gravity | 9.80665 | m/s2 | |
| atm | standard atmosphere | 101,325 | Pa | |
| H0 | hubble constant* | 70.8 2.29 | × 10−18 | km/s/Mpc s−1 |
| mercury | venus | earth | mars | |
|---|---|---|---|---|
| traditional symbol | ☿ | ♀ | ♁ | ♂ |
| mass (1024 kg) | 0.3302 | 4.8685 | 5.9736 | 0.64185 |
| mean radius (km) | 2439.7 | 6051.8 | 6371.0 | 3390 |
| equatorial radius (km) | 2439.7 | 6051.8 | 6378.1 | 3397 |
| polar radius (km) | 2439.7 | 6051.8 | 6356.8 | 3375 |
| flattening factor | 0.0000 | 0.0000 | 0.00335 | 0.00648 |
| moment of inertia constant | 0.33 | 0.33 | 0.3308 | 0.366 |
| obliquity of axis (°) | 0.01 | 177.36 | 23.45 | 25.19 |
| semimajor axis (106 km) | 57.91 | 108.21 | 149.60 | 227.92 |
| perihelion (106 km) | 46.00 | 107.48 | 147.09 | 206.62 |
| aphelion (106 km) | 69.82 | 108.94 | 152.10 | 249.23 |
| orbital eccentricity | 0.2056 | 0.0067 | 0.0167 | 0.0935 |
| orbital inclination (°) | 7.00 | 3.39 | 0 (by definition) | 1.850 |
| siderereal orbit (days) | 87.969 | 224.701 | 365.256 | 686.980 |
| tropical orbit (days) | 87.968 | 224.695 | 365.242 | 686.973 |
| sideral period (hours) | 1407.6 | −5832.5 | 23.9345 | 24.6229 |
| length of day (hours) | 4222.6 | 2802.0 | 24.0000 | 24.6597 |
| mean surface pressure (kPa) | 10−12 | 9,200 | 101.325 (by convention) | 0.638 |
| mean surface temperature (K) | 440 | 737 | 288 | 210 |
| blackbody temperature (K) | 442.5 | 231.7 | 254.3 | 210.1 |
| natural satellites | none | none | 1 | 2 |
| planetary ring system | none | none | none | none |
| jupiter | saturn | uranus | neptune | |
|---|---|---|---|---|
| traditional symbol | ♃ | ♄ | ♅, ⛢ | ♆ |
| mass (1024 kg) | 1,898.6 | 568.46 | 86.832 | 102.43 |
| mean radius (km) | 69,911 | 58,232 | 25,362 | 24,624 |
| equatorial radius (km) | 71,492 | 60,268 | 25,559 | 24,764 |
| polar radius (km) | 66,854 | 54,364 | 24,973 | 24,341 |
| flattening factor | 0.06487 | 0.09796 | 0.02293 | 0.01708 |
| moment of inertia constant | 0.254 | 0.210 | 0.225 | ? |
| obliquity of axis (°) | 3.13 | 26.73 | 97.77 | 28.32 |
| semimajor axis (106 km) | 778.57 | 1,433.53 | 2,872.46 | 4,495.06 |
| perihelion (106 km) | 740.52 | 1,352.55 | 2,741.30 | 4,444.45 |
| aphelion (106 km) | 816.62 | 1,514.50 | 3,003.62 | 4,545.67 |
| orbital eccentricity | 0.0489 | 0.0565 | 0.0457 | 0.0113 |
| orbital inclination (°) | 1.304 | 2.485 | 0.772 | 1.769 |
| siderereal orbit (days) | 4,332.589 | 10,759.22 | 30,685.4 | 60,189 |
| tropical orbit (days) | 4,330.595 | 10,746.94 | 30,588.740 | 59,799.9 |
| sideral period (hours) | 9.9250 | 10.656 | −17.24 | 16.11 |
| length of day (hours) | 9.9259 | 10.656 | 17.24 | 16.11 |
| mean surface pressure (kPa) | n/a | n/a | n/a | n/a |
| mean surface temperature (K) | 165 | 134 | 76 | 72 |
| blackbody temperature (K) | 110.0 | 81.1 | 58.2 | 46.6 |
| natural satellites | 63 | 47 | 27 | 13 |
| planetary ring system | 1 | extensive | 13 | 9 |
| discovery | antiquity | antiquity | William Herschel 13 March 1781 | Johann Galle 23 September 1846 |
| ceres | comet halley | pluto | eris | |
|---|---|---|---|---|
| traditional symbol(s) | ♇ | |||
| family | main belt asteroid | short period comet | kuiper belt object | trans-neptunian object |
| mass (1024 kg) | 0.00095 | 0.0075 | 0.0125 | ? |
| mean radius (km) | 975 × 909 | 16 × 8 | 1195 | 1350 |
| obliquity of axis (°) | ? | ? | 122.53 | ? |
| semimajor axis (106 km) | 413.715 | 2684 | 5906.38 | 10,160 |
| perihelion (106 km) | 380.612 | 5235 | 4436.82 | 5710 |
| aphelion (106 km) | 446.818 | 89.8 | 7375.93 | 14,602.3 |
| orbital eccentricity | 0.080 | 0.967 | 0.2488 | 0.4378 |
| orbital inclination (°) | 10.587 | 18 | 17.16 | 43.993 |
| siderereal orbit (days) | 1679.819 | −28,361–603 | 90,465 | 203,500 |
| tropical orbit (days) | ? | ? | 90,588 | ? |
| sideral period (hours) | 9.0744 | ? | −153.2928 | ? |
| length of day (hours) | ? | ? | 153.2820 | ? |
| mean surface pressure (kPa) | ? | ? | 0.0003 | ? |
| mean surface temperature (K) | 167 | ? | 50 | ? |
| blackbody temperature (K) | ? | ? | 37.5 | ? |
| natural satellites | 0 | 0 | 4 | 1 |
| discovery | Giuseppe Piazzi 1 January 1801 | antiquity | Clyde Tombaugh 18 February 1930 | Brown, Trujillo, Rabinowitz 5 January 2005 |
| io | europa | ganymede | callisto | |
|---|---|---|---|---|
| mass (1022 kg) | 8.932 | 4.800 | 14.819 | 10.759 |
| mean radius (km) | 1821.6 | 1560.8 | 2631.2 | 2410.3 |
| semimajor axis (km) | 421,600 | 670,900 | 1,070,400 | 1,882,700 |
| orbital eccentricity | 0.004 | 0.0101 | 0.0015 | 0.007 |
| orbital inclination (°) | 0.04 | 0.47 | 0.21 | 0.51 |
| siderereal orbit (days) | 1.769138 | 3.551181 | 7.154553 | 16.689018 |
| discovery | Galileo Galilei 7 January 1610 | |||
| moon | titan | triton | charon | |
|---|---|---|---|---|
| traditional symbol(s) | ☾ ☽ | |||
| satellite of … | earth | saturn | neptune | pluto |
| mass (1022 kg) | 7.349 | 13.45 | 2.14 | 0.162 |
| mean radius (km) | 1737.1 | 2575 | 1353.4 | 593 |
| semimajor axis (km) | 384,400 | 1,221,850 | 354,760 | 19,600 |
| perigee (km) | 363,300 | – | – | – |
| apogee (km) | 405,500 | – | – | – |
| orbital eccentricity | 0.0549 | 0.0292 | 0.000016 | 0.0002 |
| orbital inclination (°) | 5.145 | 0.33 | 157.345 | 0.0 |
| siderereal orbit (days) | 27.3217 | 15.945421 | −5.876854 | 6.38725 |
| mean surface pressure (kPa) | 10−13 | 150 | ? | ? |
| mean surface temperature (K) | 100–400 | 95 | ? | ? |
| discovery | antiquity | Christiaan Huygens 25 March 1655 | William Lassell 10 October 1846 | James Christy 22 June 1978 |
| sun | proxima centauri | sirius | betelgeuse | |||
|---|---|---|---|---|---|---|
| traditional symbol | ☉ | |||||
| mass | 1.989 × 1030 kg | 0.12 m☉ | 2.14 m☉ | 12-17 m☉ | ||
| radius | 6.960 × 108 m | 0.12 r☉ | 1.68 r☉ | 650 r☉ | ||
| luminosity | 3.839 × 1026 W | 0.0009 L☉ | 26.1 L☉ | 9400 L☉ | ||
| temperature | 5780 K | 2670 K | 9900 K | 3100 K | ||
| type | G2 (main sequence) | M5 (red dwarf) | A1 (main sequence) | M1 (red supergiant) | ||
| distance from earth | 1.496× 1011 m | 4.27 light years | 8.57 light years | 520 light years | ||
