Arche

Discovery
Arche was discovered by Scott S. Sheppard at the Mauna Kea Observatory in Hawaii on October 31st 2002.

In-Depth
Arche is a member of the Carme group, a family of Jovian satellites that have similar orbits, appearances and therefore must have similar origins. The group most likely started of as a D-type asteroid (possibly from the Hilda family or the Jupiter Trojans that suffered a collision, which broke of a number of pieces, either before or after being captured in Jupiter's gravity. The largest remaining chunk of the resulting collision (which still retains 99% of the group's mass) was named "Carme" and the smaller pieces became the other 16 members of the group.

All of the Carme moons are retrograde, they orbit in the opposite direction of the parent planet's rotation. Their orbits are also eccentric (elliptical rather than circular) and highly inclined with respect to Jupiter's equatorial plane. The Carme moons are similar in colour - light red - except for Kalyke, which is considerably redder than all the other moons in the group. These characteristics support the idea that the Carme satellites began as one single asteroid, rather than forming as part of Jupiter's original system. None of the Carme members are big enough to pull themselves into a sphere shape, so they're probably irregularly shaped.

Arche has a mean radius of 1 miles (1.5 kilometres). The satellite takes 732 Earth days to complete one orbit, with an average distance of 14.5 million miles (23.4 million kilometres) away from Jupiter.

Namesake
Satellites of Jupiter are named after Zeus/Jupiter's lovers and descendants. Names of satellites with a prograde orbit generally end with the letter "a" (although an "o" has been reserved for special cases) and names of satellites with a retrograde orbit end with the letter "e".

Originally designated S/2002 J1, Arche was named after the Muses, who were daughters of Zeus, the Greek equivalent of the Roman god Jupiter. Arche translates to "beginning".