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Callirrhoe (moon)

Spacewatch image from 1999
Discovered bySpacewatch
Discovery siteKitt Peak National Observatory[1]
Discovery dateOctober 1999
Jupiter XVII
Orbital characteristics[4]
24102000 km
−758.82 d (2.1 yr)
Satellite ofJupiter
GroupPasiphae group
Physical characteristics
Albedo0.04 (assumed)

Callirrhoe (/kəˈlɪr./;[5] Greek: Καλλιρρόη), also known as Jupiter XVII, 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,[1] and originally designated as asteroid (1999 UX18).[3][6] It was discovered to be in orbit around Jupiter by Tim Spahr on July 18, 2000, and then given the designation S/1999 J 1.[2][7] It was the 17th confirmed moon of Jupiter.[1]

Callirrhoe has an apparent magnitude of 20.7,[8] making it even fainter than dwarf planet Eris at magnitude 18.7.[9] Jupiter is about 2.5 billion times brighter than Callirrhoe.[10]

Callirrhoe is about 8.6 kilometers in diameter,[8] 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.[1]

It was named in October 2002 after Callirrhoe, daughter of the river god Achelous, one of Zeus' (Jupiter's) many conquests.[11]

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 Callirrhoe on January 10, 2007.[12]


  1. ^ a b c d "New Outer Satellite of Jupiter Discovered". Minor Planet Center. Retrieved July 23, 2009.
  2. ^ a b c d Brian G. Marsden (July 20, 2000). "IAUC 7460: S/1999 J 1". IAU. Archived from the original on April 26, 2006. Retrieved November 22, 2005.
  3. ^ a b "New moon of Jupiter found". SpaceFlight Now (University of Arizona News Release). Retrieved July 23, 2009.
  4. ^ S.S. Sheppard (2019), Moons of Jupiter, Carnegie Science, on line
  5. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  6. ^ MPS 7418 (Minor Planet Circulars Supplement); not available on-line
  7. ^ MPEC 2000-Y16: S/1975 J 1 = S/2000 J 1, S/1999 J 1 2000-12-19 (discovery and ephemeris)
  8. ^ a b "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). April 3, 2009. Retrieved July 23, 2009.
  9. ^ "AstDys (136199) Eris Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved March 16, 2009.
  10. ^ (5th root of 100)^(20.7-(-2.8))=2.51 billion
  11. ^ IAUC 7998: Satellites of Jupiter[permanent dead link] 2002 October 22 (naming the moon)
  12. ^ "New Horizons Jupiter Encounter Timeline".

External links