Discovery [1] | |
---|---|
Discovered by | Seth B. Nicholson |
Discovery site | Lick Observatory |
Discovery date | 21 July 1914 |
Designations | |
Designation | Jupiter IX |
Pronunciation | /səˈnoʊpiː/[2][3] |
Named after | Σινώπη Sinōpē |
Adjectives | Sinopean[4] /saɪnəˈpiːən/[5] |
Orbital characteristics [6] | |
Epoch 23 March 2018 (JD 2458200.5) | |
Observation arc | 103.87 yr (37,938 days) |
0.1629144 AU (24,371,650 km) | |
Eccentricity | 0.3366550 |
–777.29 d (2.13 years) | |
71.53524° | |
0° 27m 47.33s / day | |
Inclination | 158.63840° (to ecliptic) |
8.61437° | |
60.30205° | |
Satellite of | Jupiter |
Group | Pasiphae group |
Physical characteristics | |
35.0±0.6 km[7] | |
13.16±0.10 h[8] | |
Albedo | 0.042±0.006[7] |
18.3[9] | |
11.1[6] | |
Sinope /səˈnoʊpiː/ is a retrograde irregular satellite of Jupiter discovered by Seth Barnes Nicholson at Lick Observatory in 1914,[1] and is named after Sinope of Greek mythology.
Sinope did not receive its present name until 1975;[10][11] before then, it was simply known as Jupiter IX. It was sometimes called "Hades"[12] between 1955 and 1975.
Sinope orbits Jupiter on a high-eccentricity and high-inclination retrograde orbit. Its orbit is continuously changing due to solar and planetary perturbations.[13] Sinope is believed to belong to the Pasiphae group of retrograde irregular moons.[14] However, given its mean inclination and different colour, Sinope could be also an independent object, captured independently, unrelated to the collision and break-up at the origin of the group.[15] The diagram illustrates Sinope's orbital elements in relation to other satellites of the group.
Sinope is also known to be in a secular resonance with Jupiter, similar to Pasiphae. However, Sinope can drop out of this resonance and has periods of both resonant and non-resonant behaviour in time scales of 107 years.[16]
From measurements of its thermal emission, Sinope has an estimated diameter of 35 km (22 mi).[7] Sinope is red (colour indices B−V=0.84, R−V=0.46),[15] unlike Pasiphae, which is grey.
Sinope's infrared spectrum is similar to those of D-type asteroids but different from that of Pasiphae.[17] These dissimilarities of the physical parameters suggest a different origin from the core members of the group.
Listed in increasing approximate distance from Jupiter | |
Inner moons | |
Galilean moons | |
Themisto | |
Himalia group (9) | |
Carpo group (2) | |
Valetudo | |
Ananke group (26) | |
Carme group (30) | |
Pasiphae group (18) | |
See also | |