Callirrhoe (moon)
Callirrhoe, also known as , is one of Jupiter's outermost natural satellites.
Discovery and Naming
Callirrhoe was imaged by Spacewatch at Kitt Peak National Observatory from October 6 through November 4, 1999, and originally designated as asteroid. It was discovered to be in orbit around Jupiter by Tim Spahr on July 18, 2000, and then given the designation . It was the 17th confirmed moon of Jupiter.It was named in October 2002 after Callirrhoe, daughter of the river god Achelous, one of Zeus's many conquests.
Orbit
Callirrhoe orbits Jupiter on a high-eccentricity and high-inclination retrograde orbit. The orbital elements are continuously changing due to solar and planetary perturbations.It belongs to the Pasiphae group, a group of retrograde moons jupiters with semi-major axes spread over 22–25 million km, inclinations between 141° and 158°, and higher eccentricities between 0.22 and 0.44.
Physical characteristics
Callirrhoe has an apparent magnitude of 20.8, making it even fainter than dwarf planet Eris at magnitude 18.7. Jupiter is about 2.1 billion times brighter than Callirrhoe.Callirrhoe's measured albedo is around 5,2%, which means its diameter is 9,6 kilometers.
While Pasiphae belongs to the grey color class, Callirrhoe falls under the light red color class, similarly to Megaclite and Sinope.
Origin
Callirrhoe probably did not form near Jupiter but was captured by Jupiter later. Callirrhoe is believed to be a fragment from a captured asteroid along with other Pasiphae group satellites.However, it falls into a different color class than Pasiphae and could therefore have been captured by Jupiter independently of the Pasiphae group.