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Elara (moon)

Elara
Elara2-LB1-mag17.jpg
Elara near the glare of bright Jupiter
Discovery
Discovered byC. D. Perrine
Discovery dateJanuary 5, 1905[1][2]
Designations
Designation
Jupiter VII
Pronunciation/ˈɛlərə/[4]
Named after
Ελάρα Elăra[3]
AdjectivesElarian /ɛˈlɛəriən/
Orbital characteristics[5]
11741000 km
Eccentricity0.217
+259.6 days
333.0°
Inclination26.63°
109.4°
143.6°
Satellite ofJupiter
GroupHimalia group
Physical characteristics
Mean diameter
78 km
Mass8.7×1017 kg[citation needed]
Mean density
2.6 g/cm3 (assumed)[6]
~0.031 m/s2 (0.003 g)
~0.052 km/s
~0.5 d (12 h)[citation needed]
Albedo0.04 (assumed)[6]
Temperature~124 K
16.6

Elara /ˈɛlərə/ is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905.[1][2] It is the eighth-largest moon of Jupiter and is named after Elara, one of Zeus's lovers and the mother of the giant Tityos.[7]

Elara did not receive its present name until 1975; before then, it was simply known as Jupiter VII. It was sometimes called "Hera"[8] between 1955 and 1975. It has a mean radius of just 43 kilometres (27 mi), thus it is 2% of the size of Europa. However, it is half the size of Himalia, so it is the second-biggest moon in the Himalia group. It might be a captured type C or D asteroid, for it reflects very little light.

Elara belongs to the Himalia group, five moons orbiting between 11 and 13 gigametres from Jupiter at an inclination of about 27.5°.[9] Its orbital elements are as of January 2000. They are continuously changing due to solar and planetary perturbations.

New Horizons encounter

In February and March 2007, the New Horizons spacecraft to Pluto captured Elara in several LORRI images from a distance of five million miles.[10]

See also

References

  1. ^ a b Perrine, C. D. (February 27, 1905). "Satellites of Jupiter". Harvard College Observatory Bulletin. 178.
  2. ^ a b Perrine, C. D. (1905). "The Seventh Satellite of Jupiter". Publications of the Astronomical Society of the Pacific. 17 (101): 62–63. Bibcode:1905PASP...17...56.. doi:10.1086/121624. JSTOR 40691209.
  3. ^ DGE en línea
  4. ^ James Knowles (1851) A Critical Pronouncing Dictionary of the English Language
  5. ^ S.S. Sheppard (2019), Moons of Jupiter, Carnegie Science, on line
  6. ^ a b "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). Retrieved August 10, 2009.
  7. ^ Marsden, Brian G. (October 7, 1975). "Satellites of Jupiter". International Astronomical Union. Archived from the original on February 22, 2014.
  8. ^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.
  9. ^ Jacobson, R. A. (2000). "The orbits of outer Jovian satellites" (PDF). Astronomical Journal. 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817.
  10. ^ Hamilton, Thomas Wm. (2013). Moons of the solar system. Strategic Book Publishing. p. 21. ISBN 1625161751.

External links