The Moons of the Solar System

Space fans! How about memorizing the moons of the solar system? There are only… nearly 200 of them orbiting the planets and dwarf planets. Here, they’re not numbered by orbital order, but instead by numerical order, or the order in which they were numbered. (There’s some debate on the order of the outer moons of Jupiter and Saturn, as the exact orbital distances aren’t clear for a few of them. Also, a few of Saturn’s moons share the same orbits as each other, and two even swap places every four years. So listing the moons in orbital order distance is hard to do.)

Bold text indicates a large, main moon (a round one), regular text a smaller moon. After that is a designation showing the group each moon belongs to. There are three groups for each planet: the small inner group that consists of tiny moons orbiting along the planet’s equator in circular orbits, the main group (large satellites) that does the same thing, and the outer group of tiny irregular moons that have wild orbits that are tilted and elliptical, far from the equator.

MERCURY

No known moons. :frowning:

VENUS

No known moons. :frowning:

EARTH

I. Moon (Main)

MARS

I. Phobos (Inner) - the innermost known moon
II. Deimos (Inner) - the outermost known moon

CERES (dwarf planet)

No known moons. :frowning:

JUPITER
Some of Jupiter’s outer moons have similar orbits to each other. This means that they can be classified into four distinct groups (in order: Himalia, Ananke, Carme, Pasiphae), each named for its largest member. Himalia is the only group that orbits forward. The other three are backward groups. There are a few moons that do not easily fit this scheme and seem to be alone.

I. Io (Main)
II. Europa (Main)
III. Ganymede (Main)
IV. Callisto (Main)
V. Amalthea (Inner)
VI. Himalia (Himalia)
VII. Elara (Himalia)
VIII. Pasiphae (Pasiphae)
IX. Sinope (Pasiphae)
X. Lysithea (Himalia)
XI. Carme (Carme)
XII. Ananke (Ananke)
XIII. Leda (Himalia)
XIV. Thebe (Inner)
XV. Adrastea (Inner)
XVI. Metis (Inner) - the innermost known moon
XVII. Callirrhoe (Pasiphae)
XVIII. Themisto (Outer forward, no group, the innermost outer moon)
XIX. Megaclite (Pasiphae) - the outermost known moon
XX. Taygete (Carme)
XXI. Chaldene (Carme)
XXII. Harpalyke (Ananke)
XXIII. Kalyke (Carme)
XXIV. Iocaste (Ananke)
XXV. Erinome (Carme)
XXVI. Isonoe (Carme)
XXVII. Praxidike (Ananke)
XXVIII. Autonoe (Pasiphae)
XXIX. Thyone (Ananke)
XXX. Hermippe (Ananke)
XXXI. Aitne (Carme)
XXXII. Eurydome (Pasiphae)
XXXIII. Euanthe (Ananke)
XXXIV. Euporie (Ananke)
XXXV. Orthosie (Ananke)
XXXVI. Sponde (Pasiphae)
XXXVII. Kale (Carme)
XXXVIII. Pasithee (Carme)
XXXIX. Hegemone (Pasiphae)
XL. Mneme (Ananke)
XLI. Aoede (Pasiphae)
XLII. Thelxinoe (Ananke)
XLIII. Arche (Carme)
XLIV. Kallichore (Carme)
XLV. Helike (Ananke)
XLVI. Carpo (Outer forward, no group, between the Himalia and the Ananke groups)
XLVII. Eukelade (Carme)
XLVIII. Cyllene (Pasiphae)
XLIX. Kore (Pasiphae)
L. Herse (Carme)
LI. Unnamed (Carme)
LII. Unnamed (Ananke)
LIII. Dia (Himalia)
LIV. Unnamed (Ananke)
LV. Unnamed (Ananke)
LVI. Unnamed (Pasiphae)
LVII. Eirene (Carme)
LVIII. Philophrosyne (Pasiphae)
LIX. Unnamed (Pasiphae)
LX. Eupheme (Ananke)
LXI. Unnamed (Carme)
LXII. Valetudo (Outer forward, no group, between the Himalia and the Ananke groups, outermost of the forward moons)
LXIII. Unnamed (Carme)
LXIV. Unnamed (Ananke)
LXV. Pandia (Himalia)
LXVI. Unnamed (Carme)
LXVII. Unnamed (Pasiphae)
LXVIII. Unnamed (Ananke)
LXIX. Unnamed (Carme)
LXX. Unnamed (Ananke)
LXXI. Ersa (Himalia)
LXXII. Unnamed (Carme)
There are seven additional moons that are not confirmed. Two are part of the Carme group, one is part of the Ananke group, one might be part of the Ananke group or might be its own group (more observations are needed), two are part of the Pasiphae group, and one might be part of the Pasiphae group or might be its own group (more observations are needed). If this last one turns out to be in its own group, it will be the outermost known moon of Jupiter.

SATURN
The outer moons of Saturn are in three groups - two inner forward groups (Gallic and Inuit) and one outer backward group (Norse). The Norse group could be subdivided further into subgroups, but there’s no agreed way to do this. The distinction between the small inner moons and the large main moons is a bit blurred - instead of an orbital distance that clearly separates them, small moons have been discovered within the realm of the main moons. They’re not quite inner moons but they’re not quite main moons either. I’ll try to indicate which moons these are and give notes as of to where they fit in the orbital scheme.

I. Mimas (Main)
II. Enceladus (Main)
III. Tethys (Main)
IV. Dione (Main)
V. Rhea (Main)
VI. Titan (Main)
VII. Hyperion (Main)
VIII. Iapetus (Main)
IX. Phoebe (Norse, but its name predates the naming system for this group of moons, having been discovered a century before the rest of its group)
X. Janus (Inner, switches orbits with Epimetheus every four years)
XI. Epimetheus (Inner, switches orbits with Janus every four years)
XII. Helene (A small moon orbiting 60 degrees ahead of Dione)
XIII. Telesto (A small moon orbiting 60 degrees ahead of Tethys)
XIV. Calypso (A small moon orbiting 60 degrees behind Tethys)
XV. Atlas (Inner)
XVI. Prometheus (Inner)
XVII. Pandora (Inner)
XVIII. Pan (Inner) - the innermost known moon
XIX. Ymir (Norse)
XX. Paaliaq (Inuit)
XXI. Tarvos (Gallic)
XXII. Ijiraq (Inuit)
XXIII. Suttungr (Norse)
XXIV. Kiviuq (Inuit)
XXV. Mundilfari (Norse)
XXVI. Albiorix (Gallic)
XXVII. Skathi (Norse)
XXVIII. Erriapus (Gallic)
XXIX. Siarnaq (Inuit)
XXX. Thrymr (Norse)
XXXI. Narvi (Norse)
XXXII. Methone (Alkyonide, orbiting between Mimas and Enceladus)
XXXIII. Pallene (Alkyonide, orbiting between Mimas and Enceladus)
XXXIV. Polydeuces (A small moon orbiting 60 degrees behind Dione)
XXV. Daphnis (Inner)
XXXVI. Aegir (Norse)
XXXVII. Bebhionn (Gallic)
XXXVIII. Bergelmir (Norse)
XXXIX. Bestla (Norse)
XL. Farbauti (Norse)
XLI. Fenrir (Norse)
XLII. Fornjot (Norse) - the outermost known moon
XLIII. Hati (Norse)
XLIV. Hyrrokkin (Norse)
XLV. Kari (Norse)
XLVI. Loge (Norse)
XLVII. Skoll (Norse)
XLVIII. Surtur (Norse)
XLIX. Anthe (Alkyonide, orbiting between Mimas and Enceladus)
L. Jarnsaxa (Norse)
LI. Greip (Norse)
LII. Tarqeq (Inuit)
LIII. Aegaeon (Inner)
There are twenty-nine additional moons that are not confirmed. Twenty-five are Norse group moons (one of which if confirmed would be farther away than Fornjot), two are Inuit group moons, one is a Gallic group moon, and one is a very small moonlet orbiting within Saturn’s rings, which would make it the innermost known moon.

URANUS
There is not enough information on Uranus’s outer moons to clearly divide them into groups, like Jupiter’s and Saturn’s. All of Uranus’s outer moons orbit backward except for Margaret (XXIII).

I. Ariel (Main)
II. Umbriel (Main)
III. Titania (Main)
IV. Oberon (Main)
V. Miranda (Main)
VI. Cordelia (Inner) - the innermost known moon
VII. Ophelia (Inner)
VIII. Bianca (Inner)
IX. Cressida (Inner)
X. Desdemona (Inner)
XI. Juliet (Inner)
XII. Portia (Inner)
XIII. Rosalind (Inner)
XIV. Belinda (Inner)
XV. Puck (Inner)
XVI. Caliban (Outer)
XVII. Sycorax (Outer)
XVIII. Prospero (Outer)
XIX. Setebos (Outer)
XX. Stephano (Outer)
XXI. Trinculo (Outer)
XXII. Francisco (Outer)
XXIII. Margaret (Outer, the only outer moon to orbit forward)
XXIV. Ferdinand (Outer) - the outermost known moon
XXV. Perdita (Inner)
XXVI. Mab (Inner)
XXVII. Cupid (Inner)

NEPTUNE
Neptune has a very traditional system of moons, but there are a few cases where the nice inner-main-outer classification of moons falls apart, with some moons taking characteristics of multiple groups. Also, Neptune’s outer moons aren’t classified into groups, but there are two pairs with very similar orbits: Sao-Laomedeia and Psamathe-Neso.

I. Triton (Hard to classify. Triton’s size and incredibly circular orbit are characteristics that are more like a main, large moon, but it orbits backwards around Neptune and at a weird angle, which makes it more like an outer, irregular moon. Take your pick as of to what group you want to classify it under.)
II. Nereid (Outer forward)
III. Naiad (Inner) - the innermost known moon
IV. Thalassa (Inner)
V. Despina (Inner)
VI. Galatea (Inner)
VII. Larissa (Inner)
VIII. Proteus (Inner/Main) (Proteus is large enough to be a main moon - even larger than Mimas, Saturn’s smallest main moon - but it’s not round. It’s the largest size that a moon can be before gravity forces it to become round. Due to its irregular shape, Proteus is usually classified as an inner moon.)
IX. Halimede (Outer backward)
X. Psamathe (Outer backward)
XI. Sao (Outer forward)
XII. Laomedeia (Outer forward)
XIII. Neso (Outer backward) - the outermost known moon
XIV. Hippocamp (Inner)

PLUTO (dwarf planet)

I. Charon (Main) - the innermost known moon
II. Nix (Inner)
III. Hydra (Inner) - the outermost known moon
IV. Kerberos (Inner)
V. Styx (Inner)

HAUMEA (dwarf planet)

I. Hiʻiaka (Inner) - the outermost known moon
II. Namaka (Inner) - the innermost known moon

MAKEMAKE (dwarf planet)

I. Unnamed (Inner)

ERIS (dwarf planet)

I. Dysnomia (Main)

Have fun memorizing all of this.

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The thing I love most about this challenge is that since the names are based on various mythologies you can also memorize the myths by putting in little stories. Two birds with one stone. Inuit mythology is quite interesting and new to me.

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Five moons of Jupiter just got names, so if you’re trying to memorize the list, you now have an updated version to memorize.

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Updated to add twenty additional moons of Saturn. Nine of the twenty are yet to be announced.

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The orbits of the remaining nine of the new twenty have been announced. Eight are Norse group moons, one is an Inuit group moon.

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