Sinope (moon)

moon of Jupiter

Sinope is a non-spherical moon of Jupiter. It was found by Seth Barnes Nicholson at Lick Observatory in 1914,[4] and is named after Sinope of Greek mythology.

Discovered byS. B. Nicholson
Discovery dateJuly 21, 1914
Orbital characteristics
Periapsis18,237,600 km
Apoapsis30,191,200 km
Mean orbit radius
23,540,000 km[1]
724.1 d (1.95 a)[1]
2.252 km/s
Inclination128.11° (to the ecliptic)
153.12° (to Jupiter's equator)[1]
Satellite ofJupiter
Physical characteristics
Mean radius
~19 km[2][3]
~4500 km2
Volume~28,700 km3
Mass7.5×1016 kg
Mean density
2.6 g/cm3 (assumed)[2]
0.014 m/s2 (0.001 g)
~0.023 km/s
Albedo0.04 (assumed)[2][3]
Temperature~124 K

Sinope did not get its present name until 1975;[5][6] before then, it was simply known as Jupiter IX. It was sometimes called "Hades"[7] between 1955 and 1975.

Sinope was the farthest known moon of Jupiter until the discovery of Megaclite in 2000. The farthest moon of Jupiter now known is S/2003 J 2.

Pasiphae group

Sinope orbits Jupiter on a high eccentricity and high inclination retrograde orbit. The orbital elements are as of January 2000.[1] They are changing a lot due to Solar and planetary perturbations. It is often believed to belong to the Pasiphaë group.[3] 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.[8] The diagram illustrates Sinope's orbital elements in relation to other moons of the group.

Physical characteristics


Sinope has an estimated diameter of 38 km (assuming an albedo of 0.04)[3] The moon is red[8] unlike Pasiphae which is grey.

Its infrared spectrum is similar to D-type asteroids also different from Pasiphae.[9] These dissimilarities of the physical parameters suggest a different origin from the core members of the group.


  1. 1.0 1.1 1.2 1.3 1.4 Jacobson, R. A. (2000). "The Orbits of the Outer Jovian Satellites". Astronomical Journal. 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817. S2CID 120372170. Archived from the original on 2019-12-13. Retrieved 2019-04-26.
  2. 2.0 2.1 2.2 "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2008-10-24. Retrieved 2008-12-12.
  3. 3.0 3.1 3.2 3.3 Sheppard, S. S.; and Jewitt, D. C.; "An Abundant Population of Small Irregular Satellites Around Jupiter", Nature, Vol. 423 (May 2003), pp. 261-263
  4. Nicholson, S. B. (1914). "Discovery of the Ninth Satellite of Jupiter". Publications of the Astronomical Society of the Pacific. 26 (155): 197–198. Bibcode:1914PASP...26..197N. doi:10.1086/122336. PMC 1090718. PMID 16586574.
  5. Nicholson, S. B. (April 1939). "The Satellites of Jupiter". Publications of the Astronomical Society of the Pacific. 51 (300): 85–94. Bibcode:1939PASP...51...85N. doi:10.1086/125010. S2CID 122937855. (in which he declines to name the recently discovered satellites (pp. 93–94))
  6. IAUC 2846: Satellites of Jupiter 1974 October 7 (naming the moon)
  7. Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4.
  8. 8.0 8.1 Grav, T.; Holman, M. J.; Gladman, B. J.; and Aksnes, K.; "Photometric Survey of the Irregular Satellites", Icarus, Vol. 166 (2003), pp. 33-45
  9. Grav, T.; and Holman, M. J. (2004). "Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal. 605 (2): L141–L144. arXiv:astro-ph/0312571. Bibcode:2004ApJ...605L.141G. doi:10.1086/420881. S2CID 15665146.

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