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Astronomy

G | Selected Moons of the Planets

AstronomyG | Selected Moons of the Planets

Note: As this book goes to press, nearly two hundred moons are now known in the solar system and more are being discovered on a regular basis. Of the major planets, only Mercury and Venus do not have moons. In addition to moons of the planets, there are many moons of asteroids. In this appendix, we list only the largest and most interesting objects that orbit each planet (including dwarf planets). The number given for each planet is discoveries through 2015. For further information see https://solarsystem.nasa.gov/planets/solarsystem/moons and https://en.wikipedia.org/wiki/List_of_natural_satellites.

Selected Moons of the Planets
Planet (moons) Satellite Name Discovery Semimajor Axis (km × 1000) Period (d) Diameter (km) Mass (1020 kg) Density (g/cm3)
Earth (1) Moon — 384 27.32 3476 735 3.3
Mars (2) Phobos Hall (1877) 9.4 0.32 23 1 × 10−4 2.0
Deimos Hall (1877) 23.5 1.26 13 2 × 10−5 1.7
Jupiter (79) Amalthea Barnard (1892) 181 0.50 200 — —
Thebe Voyager (1979) 222 0.67 90 — —
Io Galileo (1610) 422 1.77 3630 894 3.6
Europa Galileo (1610) 671 3.55 3138 480 3.0
Ganymede Galileo (1610) 1070 7.16 5262 1482 1.9
Callisto Galileo (1610) 1883 16.69 4800 1077 1.9
Himalia Perrine (1904) 11,460 251 170 — —
Saturn (82) Pan Voyager (1985) 133.6 0.58 20 3 × 10−5 —
Atlas Voyager (1980) 137.7 0.60 40 — —
Prometheus Voyager (1980) 139.4 0.61 80 — —
Pandora Voyager (1980) 141.7 0.63 100 — —
Janus Dollfus (1966) 151.4 0.69 190 — —
Epimetheus Fountain, Larson (1980) 151.4 0.69 120 — —
Mimas Herschel (1789) 186 0.94 394 0.4 1.2
Enceladus Herschel (1789) 238 1.37 502 0.8 1.2
Tethys Cassini (1684) 295 1.89 1048 7.5 1.3
Dione Cassini (1684) 377 2.74 1120 11 1.3
Rhea Cassini (1672) 527 4.52 1530 25 1.3
Titan Huygens (1655) 1222 15.95 5150 1346 1.9
Hyperion Bond, Lassell (1848) 1481 21.3 270 — —
Iapetus Cassini (1671) 3561 79.3 1435 19 1.2
Phoebe Pickering (1898) 12,950 550 (R)1 220 — —
Uranus (27) Puck Voyager (1985) 86.0 0.76 170 — —
Miranda Kuiper (1948) 130 1.41 485 0.8 1.3
Ariel Lassell (1851) 191 2.52 1160 13 1.6
Umbriel Lassell (1851) 266 4.14 1190 13 1.4
Titania Herschel (1787) 436 8.71 1610 35 1.6
Oberon Herschel (1787) 583 13.5 1550 29 1.5
Neptune (14) Despina Voyager (1989) 53 0.33 150 — —
Galatea Voyager (1989) 62 0.40 150 — —
Larissa Reitsema, et al (1981) 74 0.55 194 — —
Proteus Voyager (1989) 118 1.12 420 — —
Triton Lassell (1846) 355 5.88 (R)2 2720 220 2.1
Nereid Kuiper (1949) 5511 360 340 — —
Pluto (5) Charon Christy (1978) 19.7 6.39 1200 — 1.7
Styx Showalter et al (2012) 42 20 20 — —
Nix Weaver et al (2005) 48 24 46 — 2.1
Kerberos Showalter et al (2011) 58 24 28 — 1.4
Hydra Weaver et al (2005) 65 38 61 — 0.8
Eris (1) Dysnomea Brown et al (2005) 38 16 684 — —
Makemake (1) (MK2) Parker et al (2016) — — 160 — —
Haumea (2) Hi’iaka Brown et al (2005) 50 49 400 — —
Namaka Brown et al (2005) 39 35 200 — —
Table G1

Footnotes

  • 1R stands for retrograde rotation (backward from the direction that most objects in the solar system revolve and rotate).
  • 2R stands for retrograde rotation (backward from the direction that most objects in the solar system revolve and rotate).
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