A moon of Jupiter was discovered by Edward Emerson Barnard on September 9, 1892. Amalthea was the first new moon of Jupiter to be discovered since Galileo Galilei discovered the Galilean moons in 1610. Amalthea is also designated as "Jupiter V". In Greek mythology, Amalthea was a nymph who nursed the infant Zeus (Jupiter) with goat's milk.

Amalthea (am'-É™l-thee'-É™, , Greek Αμάλθεια) is the third moon of Jupiter (in order of distance from the planet), and the fifth in order of discovery, hence its Roman numeral designation of Jupiter V. It was discovered on September 9 1892 by Edward Emerson Barnard using the 36 inch (91 cm) refractor telescope at Lick Observatory. Amalthea was the last moon to be discovered by direct visual observation (as opposed to photographically), and was the first new moon of Jupiter to be discovered since Galileo Galilei discovered the Galilean moons in 1610.

In Greek mythology, Amalthea (in Greek, Αμαλθεια — "tender goddess") is the most often mentioned among foster-mothers of Zeus. She is sometimes represented as the goat who suckled the infant-god in a cave in Mount Aigaion ("Goat Mountain") in Crete, sometimes as a goat-tending nymph of uncertain parentage (daughter of Oceanus, Haemonius, Olen, or Melisseus), who brought him up on the milk of her goat. Derived from the goddess of plenty in earlier traditions that were superseded by the Greek, her bountiful goat horn is depicted near the goat that symbolizes her in the zodiac.