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.

Orbit change

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 change

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.

References change

  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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