Callirrhoe orbits Jupiter (at an average distance of 23.3 million km) on a high-eccentricity (0.33) and high-inclination (147° toecliptic) retrograde orbit.[5] The orbital elements are continuously changing due tosolar and planetary perturbations.
It belongs to thePasiphae 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.
Callirrhoe has anapparent magnitude of 20.8,[7] making it even fainter thandwarf planetEris at magnitude 18.7.[13] Jupiter is about 2.1 billion times brighter than Callirrhoe.[b]
Callirrhoe's measured albedo is around 5.2%, which means its diameter is 9.6 kilometers.[6]
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 toMegaclite andSinope.[14]
Callirrhoe probably did not form near Jupiter but was captured by Jupiter later. Callirrhoe is believed to be a fragment from a capturedasteroid along with other Pasiphae group satellites.[15][16]
However, it falls into a different color class than Pasiphae and could therefore have been captured by Jupiter independently of the Pasiphae group.
Callirrhoe imaged by theLORRI instrument aboardNew Horizons
TheNew Horizons spacecraft flew through the Jovian system in early 2007, using Jupiter for agravity assist to shorten its journey toPluto. As a navigation exercise,New Horizons imaged Callirrhoe from a distance on 10 January 2007 using itsLORRI instrument.[17]
^The discovery is credited to the team of astronomers consisting of J. V. Scotti, T. B. Spahr, R. S. McMillan, J. A. Larson, J. Montani, A. E. Gleason, and T. Gehrels.[2]
^abSheppard, Scott."Scott S. Sheppard - Jupiter Moons".Department of Terrestrial Magnetism. Carnegie Institution for Science. Retrieved26 November 2020.
