Steven Dutch, Professor Emeritus, Natural and Applied Sciences,University of Wisconsin - Green Bay

Vital Statistics

Jupiter is Huge

Structure of Jupiter

Jupiter's Moons

Jupiter has at least 63 satellites as of 2008, numbered in order of discovery. Only the four largest(Galilean) satellites and one other have generally used names.

Small Inner Moons

Jupiter XV and XVI

Discovered by the Voyager spacecraft. They orbit outside Jupiter's ring about 80,000 milesfrom Jupiter's center in 7 hours, and are probably less than 40 km in diameter.

Amalthea (Jupiter V)

Jupiter XIV (Thebe)

Orbits between Amalthea and Io, about 160,000 miles fromJupiter. It is about 30 miles in diameter.

The Galilean Satellites

Io (Jupiter I)

Europa (Jupiter II)

Ganymede (Jupiter III)

Callisto (Jupiter IV)

The Small Outer Moons

None of these have been imaged at close range by spacecraft.

Jupiter VI, VII, X and XIII

Other Moons

Names of Minor Satellites

Galileo's discovery of the four large moons presented an unprecedented problem: what to name new objects in the Solar System. Galileo - no dummy - wanted to call them the "Medicean stars" in an effort to secure patronage from the powerful Medici family. The suggestion met with little approval. The moons should obviously be named for mythological characters connected with Jupiter but subordinate. Anyone who knows mythology knows that leaves out his wife Juno. Anyway, she has an asteroid named after her. However, Jupiter's principal hobby was having love affairs (Juno's was breaking them up and inflicting horrible vengeance on the lovers). So, following a suggestion by astronomer Simon Marius, Jupiter's satellites were named after Jupiter's lovers.

Oh, Ganymede was a boy. The ancient Greeks were cool with that.

Even Jupiter's colossal libido could hardly keep up with the tally of Jovial satellites, so beginning with satellite XXXIV (Euporie), satellites can also be named for descendants of Zeus.


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Created 20 May 1997, Last Update 11 January 2020