Moon Pasiphae

It was discovered in 1908 by Philibert Jacques Melotte and later named after the mythological Pasiphaë, wife of Minos and mother of the Minotaur from Greek legend.

Pasiphae

Pasiphae photographed by the Haute-Provence Observatory in August 1998
Discovery
Discovered by	Philibert J. Melotte
Discovery site	Royal Observatory, Greenwich
Discovery date	27 January 1908
Designations
Designation	Jupiter VIII
Pronunciation	/pəˈsɪfeɪ.iː/
Named after	Πασιφάη Pāsiphaē
Alternative names	1908 CJ
Adjectives	Pasiphaëan /ˌpæsɪfeɪˈiːən/
Orbital characteristics
Epoch 23 March 2018 (JD 2458200.5)
Observation arc	110.34 yr (40,303 days)
Semi-major axis	0.1551422 AU (23,208,940 km)
Eccentricity	0.6110162
Orbital period (sidereal)	–722.34 d
Mean anomaly	259.25505°
Mean motion	0° 29m 54.18s / day
Inclination	153.40903° (to ecliptic)
Longitude of ascending node	19.11682°
Argument of perihelion	241.59647°
Satellite of	Jupiter
Group	Pasiphae group
Physical characteristics
Mean diameter	57.8±0.8 km
Mass	1.72×1017 kg (calculated)
Mean density	1.70 g/cm3 (assumed)
Albedo	0.044±0.006
Apparent magnitude	16.9
Absolute magnitude (H)	10.1

The moon was first spotted on a plate taken at the Royal Greenwich Observatory on the night of 28 February 1908. Inspection of previous plates found it as far back as January 27. It 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.

Pasiphae did not receive its present name until 1975; before then, it was simply known as Jupiter VIII. It was sometimes called "Poseidon" between 1955 and 1975.

 

Pasiphae orbits Jupiter on a high eccentricity and high inclination retrograde orbit. It gives its name to the Pasiphae 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. The diagram illustrates its orbit in relation to other retrograde irregular satellites of Jupiter. The eccentricity of selected orbits is represented by the yellow segments (extending from the pericentre to the apocentre). The outermost regular satellite Callisto is located for reference.

Pasiphae is also known to be in a secular resonance with Jupiter (tying the longitude of its perijove with the longitude of perihelion of Jupiter).

 

With a diameter estimated at 58 km, Pasiphae is the largest retrograde and third largest irregular satellite after Himalia and Elara.

Spectroscopical measurements in infrared indicate that Pasiphae is a spectrally featureless object, consistent with the suspected asteroidal origin of the object. Pasiphae is believed to be a fragment from a captured asteroid along with other Pasiphae group satellites.

In the visual spectrum the satellite appears grey (colour indices B-V=0.74, R-V=0.38) similar to C-type asteroids.

• Irregular satellite