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C O U R S E 
Moons of Our Solar System
David Rothery, The Open University
C O U R S E   L E C T U R E 
Naming Moons
Notes taken on January 23, 2017 by Edward Tanguay
the right to name moons and features on their surfaces belongs to a body known as the International Astronomical Union (IAU)
founded in 1919
if you find a new moon, you suggest a name to the IAU but they don't have to accept it
today, when a moon is discovered
it is given a provisional name, e.g. S/2005 P1
S = Satellite
2005 = year of discovery
P = primary body, in this case, Pluto
1 = first moon of Pluto discovered that year
later when the discovery has been confirmed, the IAU gives it an official, permanent name
in this case, S/2005 P1 became Hydra
named after the snake-headed monster killed by Hercules
but why Hydra
when a new moon is discovered, it is given a name that fits in with the theme for names that have already been chosen for moons of that planet
moons of Pluto are named after figures with a connection to Hades
Galileo started this tradition
when he discovered the first four moons of Jupiter, there were no rules about naming moons
he used Roman numerals, so we had Jupiter I, Jupiter II, etc.
Simon Marius, a rival of Galileo
proposed a mythological theme
since the planet was named after the Roman god Jupiter, or Zeus, why not name the moons after the lovers of Zeus
discovered in 1610
mortal lover of Zeus
ancestor of Hercules
Hera turned her into a cow
mother of King Minos of Crete
abducted by Zeus in the form of a white bull
mentioned in Iliad
homeland was Troy
son of Tros
abducted by Zeus in the form of an eagle
Homer describes him as the most beautiful of mortals
daughter of Lycaon, king of Arcadia
took a vow to remain a virgin
to have sex with her, Zeus disguised himself as Artemis (Diana) herself, in order to lure her into his embrace
Callisto was discovered pregnant and was then turned into a bear
gave birth to a son called Arcas
Zeus placed them both in the sky as the constellations Ursa Major, called Arktos [αρκτος], the "Bear" and Ursa Minor.
16 newer moons are named after other relations with Zeus, e.g.
1892 Amalthea
the most-frequently mentioned foster-mother of Zeus
located in Crete
1904 Himalia
a nymph of the eastern end of the island of Rhodes, Zeus was enamoured with her and she produced three sons with him
1905 Elara
Zeus fell in love with Elara and hid her from his wife Hera's jealousy by placing her deep beneath the Earth. This was where she gave birth to Tityos, a giant who is sometimes said to be the son of Gaia, the Earth goddess, for this reason. It is further added that Elara died in labour because of the enormous size of her baby
1974 Leda
admired by Zeus, who seduced her in the guise of a swan
moons of Saturn
five largest moons were discovered by Christian Huegens (1629-1695)
and Giovanni Domenico Cassini (1625-1712)
Huegens followed Galileo's conventions and gave the moons numbers rather than names
when Sir William Hershel (1738-1822) discovered two other moons of Saturn
also declined to name them
his son, Sir John Hershel, settled the matter
since Saturn was the Greek equivalent of Cronos, the leader of the Titans, Sir John named the largest moon Titan
the other moons were named after other Titans
son of Uranus and Gaia
father of Atlas, Prometheus, Epimetheus and Menoetius.
daughter of Uranus and Gaia
wife of her brother the Titan-god Oceanus
daughter of Okeanos and Tethys, hence an Oceanid, a water-nymph. She is otherwise called a daughter of Gaia
daughter of the earth goddess Gaia and the sky god Uranus, and sister and wife to Cronus
the two innermost moons were named after the Titan's half brothers, two giants
Mimas was one of the Giants, the offspring of Gaia, born from the blood of the castrated Uranus
one of the Giants, the offspring of Gaia (Earth), and Uranus (Sky). Enceladus was the traditional opponent of Athena during the Gigantomachy, the war between the Giants and the gods, and was said to be buried under Mount Etna in Sicily
the pace of discovers meant that astronomers were running out of Greek and Roman names
so gods from other cultures are used
named after monstrous Norse wolf Fenrisulfr
Sir John Hershel
also discovered moons of Uranus, the planet discovered by his father
Uranus is the god of the air
took his inspiration from English literature
Oberon (1787)
Oberon, the king of the fairies in Shakespeare's A Midsummer Night's Dream.
Titania (1787)
Titania, the queen of the fairies in Shakespeare's A Midsummer Night's Dream
named after the leading sylph in The Rape of the Lock
also the name of the spirit who serves Prospero in Shakespeare's The Tempest
Umbriel is the "dusky melancholy sprite" in Alexander Pope's The Rape of the Lock, and the name suggests the Latin umbra, meaning shadow
as more moons were discovered, they were named after characters in Shakespeare's plays
moon of Uranus
named after the daughter of Polonius in Hamlet
King Lear
Much Ado About Nothing
Neptune's first moon
discovered by William Lassell (1799-1880) but he had nothing to do with naming it
naming duties fell to the French astronomer Camille Flammarion
carried on with the mythical theme
Neptune's moon was named Triton, the Greek sea god Triton [Τρίτων], the son of Poseidon (Neptune)
second moon
named after the Nereids, sea-nymphs of Greek mythology and attendants of the god Poseidon
later moons were also named after water spirits
a nymph from Thessaly
an early sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea"
Galatea [Γαλάτεια]
"she who is milk-white"
the statue carved of ivory by Pygmalion of Cyprus, which then came to life
1887 tiny moons
Phobos ("fear")
Deimos ("terror")
Phobos (panic/fear) and Deimos (terror/dread) accompanied their father Ares, god of war, into battle
dwarf planets
Pluto, the god of the underworld
moons are related to Hades
Charon [KAIR-on]
the boatman who ferried the dead across the river Styx
the many-headed dog
the snake-headed monster