Sinope (moon)

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Discovered by S. B. Nicholson
Discovery date July 21, 1914
Shortest distance from what it orbits 18,237,600 km
Longest distance from what it orbits 30,191,200 km
Avgdistance from the center of its orbital path 23,540,000 km[1]
How long it takes to complete an orbit 724.1 d (1.95 a)[1]
Average speed 2.252 km/s
Angle above the reference plane
128.11° (to the ecliptic)
153.12° (to Jupiter's equator)[1]
What it orbits Jupiter
Size and other qualities
Average radius ~19 km
Volume ~28,700 km³
Mass 7.5×1016 kg
Average density 2.6 g/cm³ (assumed)
Surface gravity 0.014 m/s2 (0.001 g)
Escape velocity ~0.023 km/s
How much light it reflects 0.04 (assumed)
Avg. surface temp. ~124 K

Sinope is a non-spherical moon of Jupiter. It was found by Seth Barnes Nicholson at Lick Observatory in 1914,[2] and is named after Sinope of Greek mythology.

Sinope did not get its present name until 1975;[3][4] before then, it was simply known as Jupiter IX. It was sometimes called "Hades"[5] 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 | change source]

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.[6] 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.[7] The diagram illustrates Sinope's orbital elements in relation to other moons of the group.

Physical characteristics[change | change source]

Sinope has an estimated diameter of 38 km (assuming an albedo of 0.04)[6] The moon is red[7] unlike Pasiphae which is grey.

Its infrared spectrum is similar to D-type asteroids also different from Pasiphae.[8] These dissimilarities of the physical parameters suggest a different origin from the core members of the group.

References[change | change source]

  1. 1.0 1.1 1.2 1.3 Jacobson, R. A. (2000). "The Orbits of the Outer Jovian Satellites". Astronomical Journal 120: pp. 2679-2686. doi:10.1086/316817. 
  2. Nicholson, S. B. (1914). "Discovery of the Ninth Satellite of Jupiter". Publications of the Astronomical Society of the Pacific 26: pp. 197-198. 
  3. Nicholson, S. B. (April 1939). "The Satellites of Jupiter". Publications of the Astronomical Society of the Pacific 51 (300): pp. 85–94.  (in which he declines to name the recently discovered satellites (pp. 93–94))
  4. IAUC 2846: Satellites of Jupiter 1974 October 7 (naming the moon)
  5. Payne-Gaposchkin, Cecilia (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4. Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. 6.0 6.1 Sheppard, S. S.; and Jewitt, D. C.; An Abundant Population of Small Irregular Satellites Around Jupiter, Nature, Vol. 423 (May 2003), pp. 261-263
  7. 7.0 7.1 Grav, T.; Holman, M. J.; Gladman, B. J.; and Aksnes, K.; Photometric Survey of the Irregular Satellites, Icarus, Vol. 166 (2003), pp. 33-45
  8. Grav, T.; and Holman, M. J. (2004). "Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal 605: pp. L141–L144. 

Other websites[change | change source]