The moon was first spotted on a plate taken at theRoyal Greenwich Observatory on the night of 28 February 1908. Inspection of previous plates found it as far back as January 27. It received theprovisional designation1908 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.[11]
Pasiphae did not receive its present name until 1975;[12] before then, it was simply known asJupiter VIII. It was sometimes called "Poseidon"[13] between 1955 and 1975.
Pasiphae orbits Jupiter on a high eccentricity and high inclination retrograde orbit. It gives its name to thePasiphae group, irregular retrograde moons orbiting Jupiter at distances ranging between 22.8 and 24.1 million km, and withinclinations ranging between 144.5° and 158.3°.[14] The orbital elements are as of January 2000.[15] They are continuously changing due tosolar 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 thepericentre to theapocentre). The outermost regular satelliteCallisto is located for reference.
Pasiphae is also known to be in asecular resonance with Jupiter (tying the longitude of its perijove with the longitude of perihelion of Jupiter).[16]
With a diameter estimated at 58 km, Pasiphae is the largest retrograde and third largest irregular satellite afterHimalia andElara.
Spectroscopical measurements ininfrared indicate that Pasiphae is aspectrally featureless object, consistent with the suspectedasteroidal origin of the object. Pasiphae is believed to be a fragment from a capturedasteroid along with other Pasiphae group satellites.[17][18]The satellite appears pale red (colour indices V=17.22 B-V=0.74, R-V=0.38) though it falls into the grey color-class ofC-type asteroids.[19]
