Callirrhoe (; Greek: ''Καλλιρρόη''), also known as , is one of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

's outer

natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriv ...

s. It is an irregular moon that orbits in a retrograde direction. Callirrhoe was imaged by

Spacewatch The Spacewatch Project is an astronomical survey that specializes in the study of minor planets, including various types of asteroids and comets at University of Arizona telescopes on Kitt Peak near Tucson, Arizona. The Spacewatch Project has be ...

Kitt Peak National Observatory The Kitt Peak National Observatory (KPNO) is a United States astronomy, astronomical observatory located on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono Oʼodham Nation, west-southwest of Tucson, Arizona. With ...

from October 6 through November 4, 1999, and originally designated as

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

. 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.

Name

It was named in October 2002 after Callirrhoe, daughter of the river god

Achelous In ancient Greek religion and Greek mythology, mythology, Achelous (also Acheloos or Acheloios) (; Ancient Greek: Ἀχελώϊος, and later , ''Akhelôios'') was the god associated with the Achelous River, the largest river in Greece. Accordi ...

, one of

Zeus Zeus (, ) is the chief deity of the List of Greek deities, Greek pantheon. He is a sky father, sky and thunder god in ancient Greek religion and Greek mythology, mythology, who rules as king of the gods on Mount Olympus. Zeus is the child ...

's (Jupiter's) many conquests.

Characteristics

Callirrhoe has an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 20.8, making it even fainter than

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...

Eris at magnitude 18.7. Jupiter is about 2.1 billion times brighter than Callirrhoe. Callirrhoe is about 9.6 kilometers in diameter, and orbits Jupiter at an average distance of 24.1 million kilometers in 747.09 days, at an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 141° to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

(140° to Jupiter's equator) with an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

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 belongs to the Pasiphae group, irregular retrograde moons orbiting Jupiter at distances ranging between 22.8 and 24.1 million kilometers, and with

s 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.

Exploration

As a navigation exercise, the ''

New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...

'' spacecraft imaged Callirrhoe on January 10, 2007.

Notes

References

External links

17th Moon of Jupiter Discovered

{{DEFAULTSORT:Callirrhoe (Moon) Pasiphae group Moons of Jupiter Irregular satellites Astronomical objects discovered in 1999 Moons with a retrograde orbit