Pasiphaë is a retrograde irregular satellite of Jupiter and with diameter estimated at 58 km, Pasiphaë is the largest retrograde and third largest irregular satellite after Himalia and Elara.
Pasiphaë is the 9th largest moon of Jupiter and 63th largest moon in the Solar System currently known.
Discovery
Pasiphaë was discovered in 1908 by Philibert Jacques Melotte. Pasiphaë was first spotted on a plate taken at the Royal Greenwich Observatory on the night of February 28, 1908. Inspection of previous plates found it as far back as January 27.
Naming
Pasiphaë initially received the provisional designation 1908 CJ, as it was not clear whether it was an asteroid or a moon of Jupiter. The recognition of the latter case came by April 10.
The moon was simply known as Jupiter VIII and sometimes called "Poseidon" between 1955 and 1975.
The moon was officially named Pasiphaë in 1975.
In Greek mythology, Pasiphaë was the daughter of Helios, the Sun, by the eldest of the Oceanids, Perse. She was given in marriage to King Minos of Crete. With Minos, she was the mother of Ariadne, Androgeus, Glaucus, Deucalion, Phaedra, and Catreus. She was also the mother of "starlike" Asterion, called by the Greeks the Minotaur, after a curse from Poseidon caused her to experience lust for and mate with a white bull sent by Poseidon.
Stats
Diameter (mean): 58 km
Apoapsis: 31,209,300 km
Periapsis: 16,980,250 km
Semi-major axis: 23,609,042 km
Orbital Period: -741.09 days
Group: Pasiphaë group
Orbit
Pasiphaë orbits Jupiter on a high eccentricity and high inclination retrograde orbit. It gives its name to the Pasiphaë group, irregular retrograde moons orbiting Jupiter at distances ranging between 22.8 and 24.1 million km, and with inclinations ranging between 144.5° and 158.3°.
The orbital elements are as of January 2000. They are continuously changing due to solar and planetary perturbations.
Pasiphae is also known to be in a secular resonance with Jupiter, which means that Jupiter's gravity tugs at them at regular intervals in a way that can modify their orbits over time.
Formation
All of the Pasiphae moons are retrograde, which means they orbit Jupiter in the opposite direction from the planet's rotation. Their orbits are also eccentric (elliptical rather than circular) and highly inclined with respect to Jupiter's equatorial plane. All of these characteristics support the idea that the Pasiphae satellites began as one or more captured asteroids, rather than forming as part of the original Jupiter system.
Physical characteristics
Spectroscopical measurements in infrared indicate that Pasiphaë is a spectrally featureless object, consistent with the suspected asteroidal origin of the object.
In the visual spectrum the satellite appears grey, similar to C-type asteroids.
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