Elara (moon)

Elara
	Low-resolution image of Elara from the New Horizons probe, March 2007
Discovery
Discovered by	Charles D. Perrine
Discovery site	Lick Observatory
Discovery date	5 January 1905
Designations
Designation	Jupiter VII
Pronunciation	/ˈɛlərə/
Named after	Ελάρα Elăra
Adjectives	Elarian /ɛˈlɛəriən/
Orbital characteristics
	Epoch 27 April 2019 (JD 2458600.5)
Observation arc	113.70 yr (41,528 days)
Semi-major axis	0.0782306 AUえーゆー (11,703,130 km)
Eccentricity	0.1961487
Orbital period (sidereal)	+258.65 d
Mean anomaly	10.93078°
Mean motion	1° 23m 30.67s / day
Inclination	30.51712° (to ecliptic)
Longitude of ascending node	90.86474°
Argument of perihelion	191.19922°
Satellite of	Jupiter
Group	Himalia group
Physical characteristics
Mean diameter	79.9±1.7 km
Albedo	0.046±0.007
Apparent magnitude	16.6
Absolute magnitude (H)	9.6

Elara /ˈɛlərə/ is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905 in photographs taken with the 36" Crossley reflecting telescope which he had recently rebuilt.^[1]^[8] 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.^[9]

Elara did not receive its present name until 1975; before then, it was simply known as Jupiter VII. It was sometimes called "Hera"^[10] 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, moons orbiting between 11 and 13 gigametres from Jupiter at an inclination of about 27.5°.^[11] Its orbital elements are as of January 2000. They are continuously changing due to solar and planetary perturbations.

Discovery

Elara was discovered by Charles Dillon Perrine of the Lick Observatory on January 6, 1905, the day after the discovery of Himalia, also by Perrine, was announced. However, poor weather conditions delayed the confirmation of the discovery till the 21st of February.^[12]

Exploration

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.^[13]

References

^ ^a ^b Perrine, C. D. (27 February 1905). "Satellites of Jupiter". Harvard College Observatory Bulletin. 178.
^ 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.
^ James Knowles (1851) A Critical Pronouncing Dictionary of the English Language
^ DGE en línea
^ ^a ^b "M.P.C. 115889" (PDF). Minor Planet Circular. Minor Planet Center. 27 August 2019.
^ ^a ^b Grav, T.; Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Nugent, C. R.; Cutri, R. M.; et al. (August 2015). "NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal. 809 (1): 9. arXiv:1505.07820. Bibcode:2015ApJ...809....3G. doi:10.1088/0004-637X/809/1/3. S2CID 5834661. 3.
^ Sheppard, Scott. "Scott S. Sheppard - Jupiter Moons". Department of Terrestrial Magnetism. Carnegie Institution for Science. Retrieved 26 November 2020.
^ 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.
^ Marsden, Brian G. (7 October 1975). "Satellites of Jupiter". International Astronomical Union. Archived from the original on 22 February 2014.
^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.
^ 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. S2CID 120372170.
^ Proctor, Mary (5 March 1905). "Jupiter's Newly Discovered Moons and Solar Cyclones". The New York Times. Retrieved 4 October 2022.
^ Hamilton, Thomas Wm. (2013). Moons of the solar system. Strategic Book Publishing. p. 21. ISBN 978-1625161758.

External links

Elara on 1998-08-15 03:21 UTC(Crédit: OHP/IMCCE/CNRS)
SkyView 23 47 09 -02 40 46
HORIZONS Web-Interface, JPL
Elara: Overview by NASA's Solar System Exploration
David Jewitt pages
"Two Irregular Satellites of Jupiter" (Himalia & Elara: Remanzacco Observatory: November 23, 2012)

[Harvard1905-1] Perrine, C. D. (27 February 1905). "Satellites of Jupiter". Harvard College Observatory Bulletin. 178.

[Perrine1905-2] 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] James Knowles (1851) A Critical Pronouncing Dictionary of the English Language

[4] DGE en línea

[MPC115889-5] "M.P.C. 115889" (PDF). Minor Planet Circular. Minor Planet Center. 27 August 2019.

[Grav2015-6] Grav, T.; Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Nugent, C. R.; Cutri, R. M.; et al. (August 2015). "NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal. 809 (1): 9. arXiv:1505.07820. Bibcode:2015ApJ...809....3G. doi:10.1088/0004-637X/809/1/3. S2CID 5834661. 3.

[SheppardMoons-7] Sheppard, Scott. "Scott S. Sheppard - Jupiter Moons". Department of Terrestrial Magnetism. Carnegie Institution for Science. Retrieved 26 November 2020.

[Perrine_1905-8] 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.

[IAUC_2846-9] Marsden, Brian G. (7 October 1975). "Satellites of Jupiter". International Astronomical Union. Archived from the original on 22 February 2014.

[Gaposchkin-10] Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.

[Jacobson_2000-11] 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. S2CID 120372170.

[12] Proctor, Mary (5 March 1905). "Jupiter's Newly Discovered Moons and Solar Cyclones". The New York Times. Retrieved 4 October 2022.

[13] Hamilton, Thomas Wm. (2013). Moons of the solar system. Strategic Book Publishing. p. 21. ISBN 978-1625161758.

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v t e Moons of Jupiter
Listed in increasing approximate distance from Jupiter
Inner moons	Metis Adrastea Amalthea Thebe
Galilean moons	Io Europa Ganymede Callisto
Themisto	Themisto
Himalia group (9)	Leda Ersa S/2018 J 2 Himalia Pandia Lysithea Elara S/2011 J 3 Dia
Carpo group (2)	S/2018 J 4 Carpo
Valetudo	Valetudo
Ananke group (26)	Euporie Jupiter LV Eupheme S/2021 J 3 Jupiter LII Jupiter LIV Mneme Euanthe S/2003 J 16 Harpalyke Orthosie S/2022 J 3 Helike S/2021 J 2 Praxidike Jupiter LXIV S/2021 J 1 S/2003 J 12 Jupiter LXVIII Thelxinoe Thyone S/2003 J 2 Ananke Iocaste Hermippe Jupiter LXX
Carme group (30)	S/2022 J 1 S/2022 J 2 S/2016 J 3 Pasithee Jupiter LXIX S/2021 J 6 S/2003 J 24 Chaldene Jupiter LXIII Isonoe S/2021 J 4 Kallichore Erinome Kale Eirene Aitne Eukelade Arche Taygete Jupiter LXXII Carme Herse Jupiter LXI Jupiter LI S/2003 J 9 Jupiter LXVI Kalyke S/2018 J 3 S/2021 J 5 S/2003 J 10
Pasiphae group (18)	Philophrosyne Eurydome Jupiter LVI S/2003 J 4 S/2016 J 4 Jupiter LXVII Hegemone Pasiphae Sponde Megaclite Cyllene Sinope Jupiter LIX Aoede Autonoe Callirrhoe S/2003 J 23 Kore
See also	Rings of Jupiter Jupiter's moons in fiction
Category

Discovery

Exploration

New Horizons encounter

See also

References

External links