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Astronomical Data

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Reference

The inner planets (terrestrial planets) Sources: NASA planetary fact sheet for Mercury, Venus, Earth, Mars
Mercury Venus Earth Mars
tradi­tional
symbol		 ☿ ♀ ♁ ♂
mass
(1024 kg)		 0.33011 4.8675 5.97217 0.64171
mean radius
(km)		 2,439.7 6,051.8 6,371.0 3,389.5
equa­torial radius (km) 2,439.7 6,051.8 6,378.1 3,396.2
polar radius
(km)		 2,439.7 6,051.8 6,356.8 3,376.2
flatten­ing
factor		 0.0000 0.0000 0.003353 0.00589
moment of inertia constant 0.33 0.33 0.3308 0.366
axial tilt
(°)		 0.034 177.36 23.44 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
sidereal
orbit (days)		 87.969 224.701 365.256 686.980
tropical
orbit (days)		 87.968 224.695 365.242 686.973
sideral period
(hours)		 1,407.6 −5,832.5 23.9345 24.6229
length of day
(hours)		 4,222.6 2,802.0 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
The outer planets (Jovian planets) Sources: NASA planetary fact sheet for Jupiter, Saturn, Uranus, Neptune
Jupiter Saturn Uranus Neptune
tradi­tional
symbol		 ♃ ♄ ♅ ♆
mass
(1024 kg)		 1,898.12 568.34 86.813 102.413
mean radius
(km)		 69,911 58,232 25,362 24,622
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
axial tilt
(°)		 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
sidereal
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		 79 62 27 14
planetary
ring system		 1 extensive 13 9
discovery antiquity antiquity William Herschel
13 March 1781		 Johann Galle
23 September 1846
Selected minor bodies Sources: JPL small-body database browser for 1 Ceres, 1P/Halley, 136199 Eris; NASA planetary fact sheet for Pluto
Ceres Halley Pluto Eris
tradi­tional
symbol(s)		 ⚳ ♇
family main belt asteroid short period comet Kuiper belt object trans-Neptunian object
mass
(1024 kg)		 0.000938 0.0075 0.01303 ?
mean radius
(km)		 469.7 5.5 1,187 1,350
axial tilt
(°)		 ? ? 122.53 ?
semi­major axis
(106 km)		 414.012 2,667.95 5,906.38 10,139.8
peri­helion
(106 km)		 382.621 87.661 4,436.82 5,671.36
ap­helion
(106 km)		 445.405 5,248.24 7,375.93 14,608.3
orbital
eccen­tricity		 0.758228 0.967143 0.2488 0.440685
orbital
inclina­tion (°)		 10.5934 −17.7373 17.16 44.0447
sidereal
orbit (days)		 1,681.63 27,509.1 90,560 203,824
tropical
orbit (days)		 ? ? ? ?
sideral period
(hours)		 9.07417 ? −153.2928 25.9
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 5 1
discovery Giuseppe Piazzi
1 January 1801		 antiquity Clyde Tombaugh
18 February 1930		 Brown, Trujillo, Rabinowitz 5 January 2005
The Galilean satellites of Jupiter Source: NASA Jovian satellite fact sheet
Io Europa Ganymede Callisto
mass
(1022 kg)		 8.932 4.800 14.819 10.759
mean radius
(km)		 1,821.6 1,560.8 2,631.2 2,410.3
semi­major
axis(km)		 421,800 671,100 1,070,400 1,882,700
orbital
eccen­tricity		 0.004 0.009 0.001 0.007
orbital
inclina­tion(°)		 0.04 0.47 0.18 0.19
sidereal
orbit (days)		 1.769138 3.551181 7.154553 16.689017
discovery Galileo Galilei
7 January 1610
Selected large satellites Sources: NASA planetary fact sheet for Moon, Titan, Triton, Charon
Moon Titan Triton Charon
tradi­tional
symbol(s)		 ☾☽
satellite
of…		 Earth Saturn Neptune Pluto
mass
(1022 kg)		 7.346 13.455 2.14 0.1586
mean radius
(km)		 1,737.4 2,575 1,353.4 603.6
semi­major
axis (km)		 384,400 1,221,830 354,760 19,596
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 0.00005
sidereal
orbit (days)		 27.3217 15.945421 −5.876854 6.3872
mean surface
pressure (kPa)		 10−13 150
mean surface
temp­erature (K)		 95–390 95
discovery antiquity Christiaan Huygens
25 March 1655		 William Lassell
10 October 1846		 James Christy
22 June 1978
Selected stars Sources: I forgot to record them
Sun Prox­ima
Cen­tauri		 Sirius Betel­geuse
tradi­tional
symbol		 ☉
mass 1.988 × 1030 kg  
 		 0.12 m☉  
 		 2.14 m☉ 12–17 m☉
radius 6.957 × 108 m  
 		 0.12 r☉  
 		 1.68 r☉ 650 r☉
luminosity 3.828 × 1026 W  
 		 0.0009 L☉  
 		 26.1 L☉ 9,400 L☉
temp­erature 5,772 K  
 		 2,670 K  
 		 9,900 K 3,100 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