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Callirrhoe ( ; Greek: ''Καλλιρρόη''), also known as (17), is one of Jupiter's outermost ''named'' 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,〔 and originally designated as asteroid ().〔〔MPS 7418 (Minor Planet Circulars Supplement); not available on-line〕 It was discovered to be in orbit around Jupiter by Tim Spahr on July 18, 2000, and then given the designation .〔〔(MPEC 2000-Y16: ''S/1975 J 1 = S/2000 J 1, S/1999 J 1'' ) 2000-12-19 (discovery and ephemeris)〕 It was the 17th confirmed moon of Jupiter.〔 Callirrhoe has an apparent magnitude of 20.7,〔 making it even fainter than dwarf planet Eris at magnitude 18.7.〔(【引用サイトリンク】publisher=Department of Mathematics, University of Pisa, Italy )〕 Jupiter is about 2.5 billion times brighter than Callirrhoe.〔(5th root of 100)^(20.7-(-2.8))=2.51 billion〕 Callirrhoe is about 8.6 kilometers in diameter,〔 and orbits Jupiter at an average distance of 24.1 million kilometers in 758 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.〔 It was named in October 2002 after Callirrhoe, daughter of the river god Achelous, one of Zeus' (Jupiter's) many conquests.〔(IAUC 7998: Satellites of Jupiter ) 2002 October 22 (naming the moon)〕 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°. As a navigation exercise, the New Horizons spacecraft imaged it on January 10, 2007.〔http://www.planetary.org/blogs/emily-lakdawalla/2007/jupiter_timeline.html〕 == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Callirrhoe (moon)」の詳細全文を読む スポンサード リンク
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