Carme was discovered on July 30, 1938 by Seth Barnes Nicholson with the 100-inch (2.5 m) Hooker telescope at the Mount Wilson Observatory in California.
With a mean radius of 14 miles (23 km), Carme is the largest member of the Carme group, a family of Jovian satellites which have similar orbits and appearance and are therefore thought to have a common origin. Carme was probably a D-type asteroid (possibly from the Hilda family or the Jupiter Trojans) that suffered a collision, which broke off a number of pieces, either before or after being captured by Jupiter's gravity. Those pieces became the other 16 moons in the Carme group. Carme still retains 99 percent of the total mass of the group.
All of the Carme moons are retrograde, which means that they orbit Jupiter in the opposite direction from the planet's rotation. Their orbits are also eccentric (elliptical rather than circular) and highly inclined with respect to Jupiter's equatorial plane. They all are very similar in color—light red—except for Kalyke, which is considerably redder than the others. All of these characteristics support the idea that the Carme satellites began as a captured asteroid, rather than forming as part of the original Jupiter system. None of the Carme members is massive enough to pull itself into a sphere, so they are probably all irregularly shaped.
At a mean distance of about 14.5 million miles (23.4 million km) from Jupiter, the satellite takes about 734 Earth days to complete one orbit.
How Carme Got its Name
Carme is named for the mother of Britomartis by the Roman god Jupiter (or Zeus in the Greek version of the myth), who became a goddess of Crete.
A name ending in "e" was chosen in accordance with the International Astronomical Union's policy for designating outer moons with retrograde orbits.