Lysithea (moon)

Lysithea

Discovery
Discovered by	S. B. Nicholson
Discovery date	July 6, 1938[1]
Designations
Adjective	Lysithean
Orbital characteristics
Mean orbit radius	11,720,000 km[2]
Eccentricity	0.11[2]
Orbital period	259.20 d (0.69 a)[2]
Average orbital speed	3.29 km/s
Inclination	28.30° (to the ecliptic) 25.77° (to Jupiter's equator)[2]
Satellite of	Jupiter
Physical characteristics
Mean radius	18 km[3]
Surface area	~4100 km²
Volume	~24,400 km³
Mass	6.3×1016 kg
Mean density	2.6 g/cm³ (assumed)[3]
Equatorial surface gravity	~0.013 m/s2 (0.001 g)
Escape velocity	~0.022 km/s
Albedo	0.04 (assumed)[3]
Temperature	~124 K

Lysithea ( /laɪˈsɪθiə/ ly-sith-ee-ə, /lɨˈsɪθiə/ li-sith-ee-ə; Greek: Λυσιθέα) is a prograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson in 1938 at Mount Wilson Observatory^[1] and is named after the mythological Lysithea, daughter of Oceanus and one of Zeus' lovers.^[4]

Lysithea didn't receive its present name until 1975; before then, it was simply known as Jupiter X. It was sometimes called "Demeter"^[5] from 1955 to 1975.

It belongs to the Himalia group, five moons orbiting between 11 and 13 Gm from Jupiter at an inclination of about 28.3°.^[2] Its orbital elements are as of January 2000. They are continuously changing due to solar and planetary perturbations.

See also

• Irregular satellites
• Jupiter's moons in fiction

References

1. ^ ^{a b} Nicholson, S.B. (1938). "Two New Satellites of Jupiter". Publications of the Astronomical Society of the Pacific 50: 292–293. Bibcode 1938PASP...50..292N. doi:10.1086/124963. http://adsabs.harvard.edu//full/seri/PASP./0050//0000292.000.html. 
2. ^ ^{a b c d e} Jacobson, R.A. (2000). "The orbits of outer Jovian satellites". Astronomical Journal 120 (5): 2679–2686. Bibcode 2000AJ....120.2679J. doi:10.1086/316817. 
3. ^ ^{a b c} "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2008-10-24. http://ssd.jpl.nasa.gov/?sat_phys_par. Retrieved 2008-12-12. 
4. ^ Marsden, B. G. (1974-10-07). "Satellites of Jupiter". IAUC Circular 2846. http://cfa-www.harvard.edu/iauc/02800/02846.html. 
5. ^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4. 

External links

• Lysithea Profile by NASA's Solar System Exploration
• David Jewitt pages
• Jupiter's Known Satellites (by Scott S. Sheppard)