The Pasiphae group is a group of retrograde

irregular satellite 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 ...

s 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 mass more than two and a half times that of all the other planets in the Solar System combined, but ...

that follow similar

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

s 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 (the same range as the

Carme group The Carme group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Carme and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 22.9 and 24.1 Gm, their orbit ...

), their

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

s between 144.5° and 158.3°, and their eccentricities between 0.25 and 0.43. Core members of the group include (negative periods indicate retrograde orbits):

Scott S. Sheppard Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System. He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Scie ...

David C. Jewitt David Clifford Jewitt (born 1958) is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Pl ...

Carolyn Porco Carolyn C. Porco (born March 6, 1953) is an American planetary scientist who explores the outer Solar System, beginning with her imaging work on the Voyager missions to Jupiter, Saturn, Uranus and Neptune in the 1980s. She led the imaging scienc ...

''Jupiter's outer satellites and Trojans'', In: ''Jupiter. The planet, satellites and magnetosphere.'' Edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon. Cambridge planetary science, Vol. 1, Cambridge, UK: Cambridge University Press, , 2004, p. 263 - 28
Full text(pdf).
The

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU) reserves names ending in -e for all retrograde moons.

Origin

The Pasiphae group is believed to have been formed when Jupiter captured an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

which subsequently broke up after a collision. The original asteroid was not disturbed heavily: the original body is calculated to have been 60 km in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

, about the same size as Pasiphae; Pasiphae retains 99% of the original body's mass. However, if Sinope belongs to the group, the ratio is much smaller, 87%. However, Nesvorny 2003, while concurring on the Ananke and Carme groups, lists only Megaclite for Pasiphae's group Unlike the Carme and Ananke groups, the theory of a single impact origin for the Pasiphae group is not accepted by all studies. This is because the Pasiphae group, while similar in semi-major axis, is more widely dispersed in inclination. Alternatively, Sinope might be not a part of the remnants of the same collision and captured independently instead.Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare ''Photometric survey of the irregular satellites'', Icarus, 166,(2003), pp. 33-45
Preprint
/ref> The differences of colour between the objects (grey for Pasiphae, light red for

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 ...

and

Megaclite Megaclite , also known as , is a natural satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2000, and given the temporary designation .

) also suggest that the group could have a more complex origin than a single collision.

Notes

References

{{DEFAULTSORT:Pasiphae group Moons of Jupiter Irregular satellites Moons with a retrograde orbit