Callirrhoe (moon)
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Callirrhoe (Template:IPAc-en; Greek: Καλλιρρόη), also known as Template:Nowrap, is one of Jupiter's outer natural satellites. It is an irregular moon that orbits in a retrograde direction. Callirrhoe was imaged by Spacewatch at Kitt Peak National Observatory from October 6 through November 4, 1999,<ref name=pr/> and originally designated as asteroid Template:Mp.<ref name="moon1999"/><ref>MPS 7418 (Minor Planet Circulars Supplement); not available on-line</ref> It was discovered to be in orbit around Jupiter by Tim Spahr on July 18, 2000, and then given the designation Template:Nowrap.<ref name="IAUC7460 "/><ref>MPEC 2000-Y16: S/1975 J 1 = S/2000 J 1, S/1999 J 1 2000-12-19 (discovery and ephemeris)</ref> It was the 17th confirmed moon of Jupiter.<ref name=pr/>
Name
It was named in October 2002 after Callirrhoe, daughter of the river god Achelous, one of Zeus's (Jupiter's) many conquests.<ref>IAUC 7998: Satellites of Jupiter 2002 October 22 (naming the moon)</ref>
Characteristics
Callirrhoe has an apparent magnitude of 20.8,<ref name="SheppardMoons"/> making it even fainter than dwarf planet Eris at magnitude 18.7.<ref name=Eris-AstDys>Template:Cite web</ref> Jupiter is about 2.1 billion times brighter than Callirrhoe.Template:Efn\approx 2.13\times10^9</math>}}
Callirrhoe is about 9.6 kilometers in diameter,<ref name="Grav2015"/> and orbits Jupiter at an average distance of 24.1 million kilometers in 747.09 days, at an inclination of 141° to the ecliptic (140° to Jupiter's equator) with an eccentricity of 0.28. This object was probably captured long ago from a heliocentric orbit and the Sun's gravitational influence makes this orbit highly erratic.<ref name=pr/>
It belongs to the Pasiphae group, irregular retrograde moons orbiting Jupiter at distances ranging between 22.8 and 24.1 million kilometers, and with inclinations ranging between 144.5° and 158.3°. However, while Pasiphae belongs to the grey color class (V=17.22 B−V=0.74, V−R=0.38), Callirrhoe falls under the light red color class (V=21.39 B−V=0.72, V−R=0.50), similarly to Megaclite and Sinope.<ref name="Grav2003">Template:Cite journal</ref>
Exploration
As a navigation exercise, the New Horizons spacecraft imaged Callirrhoe on January 10, 2007.<ref>Template:Cite web</ref>