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

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

'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 often colloquially referred to as ''moons'' ...

s. It is an

irregular moon In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular s ...

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, in the United States. The Spa ...

Kitt Peak National Observatory The Kitt Peak National Observatory (KPNO) is a United States 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 more than ...

from October 6 through November 4, 1999, and originally designated as asteroid . 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 Callirrhoe (, grc, Καλλιρρόη; also Callirhoe) may refer to: * Callirhoe (mythology), several figures in Greek mythology, including: ** Callirrhoe (Oceanid), daughter of Oceanus and Tethys ** Callirrhoe (daughter of Achelous) * Callirrhoe ...

, daughter of the river god

Achelous In ancient Greek religion and 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. According to Hesiod, he ...

, one of

Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label= genitive Boeotian Aeolic and Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label= genitive el, Δίας, ''Días'' () is the sky and thunder god in ancient Greek reli ...

' (Jupiter's) many conquests.

Characteristics

Callirrhoe has an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 20.7, making it even fainter than

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to ...

Eris at magnitude 18.7. Jupiter is about 2.5 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 the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agains ...

(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 The Pasiphae group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Pasiphae and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 22.8 and 24.1 million km (th ...

, 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°.

Exploration

As a navigation exercise, the '' New Horizons'' 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