Himalia (moon)

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Himalia as seen by Cassini-Huygens
Discovered byC. D. Perrine
Discovery dateDecember 3, 1904
Orbital characteristics
Periapsis9,782,900 km
Apoapsis13,082,000 km
Mean orbit radius
11,460,000 km[1]
250.56 d (0.704 a)[1]
3.312 km/s
Inclination27.50° (to the ecliptic)
29.59° (to Jupiter's equator)[1]
Satellite ofJupiter
Physical characteristics
Mean radius
85 km
~90,800 km²
Volume~2,570,000 km³
Mass6.7×1018 kg
Mean density
2.6 g/cm³ (assumed)
~0.062 m/s2 (0.006 g)
~0.100 km/s
7.782 h[2]
Temperature~124 K

Himalia is the biggest non-spherical moon of Jupiter. It was found by Charles Dillon Perrine at the Lick Observatory on December 3, 1904.[4] It is named after the nymph Himalia who bore three sons of Zeus (the Greek equivalent of Jupiter).

Name[change | change source]

Himalia did not get its present name until 1975;[5] before then, it was simply known as Jupiter VI or Jupiter Satellite VI, although calls for a full name appeared shortly after its and Elara's discovery. A.C.D. Crommelin wrote in 1905,

Unfortunately the numeration of Jupiter's satellites is now in precisely the same confusion as that of Saturn's system was before the numbers were abandoned and names substituted. A similar course would seem to be advisable here; the designation V for the inner satellite was tolerated for a time, as it was considered to be in a class by itself; but it has now got companions, so that this subterfuge disappears. The substitution of names for numerals is certainly more poetic.[6]

The moon was sometimes called Hestia,[7] after the Greek goddess, from 1955 to 1975.

Orbit[change | change source]

It is the biggest member of the group that bears its name, the moons orbiting between 11.4 and 13 million kilometers from Jupiter at an inclination of about 27.5°.[8] The orbital elements are as of January 2000.[1] They are changing a lot due to Solar and planetary perturbations.

Physical characteristics[change | change source]

A day on Himalia is only about 7 3/4 hours long.[9] Himalia appears grey, like the other members of its group, similar to a C-type asteroid.[10] Measurements by Cassini confirm a featureless spectrum, with a slight absorption at 3 μm which could indicate the presence of water.[11]

Exploration[change | change source]

In November 2000, the Cassini spacecraft, going to Saturn, made a number of pictures of Himalia, including photos from a distance as close as 4.4 million km. The moon covers only a few pixels, but seems to be a stretched object with axes 150 ± 20 and 120 ± 20 km, close to the Earth-based estimations.[3]

In February and March 2007, the New Horizons spacecraft to Pluto made a series of pictures of Himalia, culminating in photos from a distance of eight million km. Again, Himalia appears only a few pixels across.

References[change | change source]

  1. 1.0 1.1 1.2 1.3 1.4 Jacobson, R. A. (2000). "The orbits of outer Jovian satellites". Astronomical Journal. 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817. S2CID 120372170.
  2. Pilcher, Frederick; Mottola, Stefano; Denk, Tilmann (2012). "Photometric lightcurve and rotation period of Himalia (Jupiter VI)". Icarus. 219 (2): 741–742. Bibcode:2012Icar..219..741P. doi:10.1016/j.icarus.2012.03.021.
  3. 3.0 3.1 Porco, Carolyn C.; et al. (March 2003). "Cassini Imaging of Jupiter's Atmosphere, Satellites, and Rings". Science. 299 (5612): 1541–1547. Bibcode:2003Sci...299.1541P. doi:10.1126/science.1079462. PMID 12624258. S2CID 20150275.
  4. "Discovery of a Sixth Satellite of Jupiter". Astronomical Journal. 24 (18): 154B. January 9, 1905.; Perrine, C. D. (January 25, 1905). "Sixth Satellite of Jupiter Confirmed (Himalaia)". Harvard College Observatory Bulletin. 175: 1. Bibcode:1905BHarO.175....1P.; Perrine, C. D. (1905). "Discovery of a Sixth Satellite to Jupiter". Publications of the Astronomical Society of the Pacific. 17: 22–23.; Perrine, C. D. (1905). "Orbits of the sixth and seventh satellites of Jupiter". Astronomische Nachrichten. 169 (3): 43–44. Bibcode:1905AN....169...43P. doi:10.1002/asna.19051690304.
  5. Marsden, B. G. (October 7, 1974). "Satellites of Jupiter". IAUC Circular. 2846.
  6. Crommelin, A. C. D. (March 10, 1905). "Provisional Elements of Jupiter's Satellite VI". Monthly Notices of the Royal Astronomical Society. 65 (5): 524–527. Bibcode:1905MNRAS..65..524C. doi:10.1093/mnras/65.5.524.
  7. Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 978-0-13-478107-5.
  8. Bagenal, Fran; Dowling, Timothy E.; McKinnon, William B. (2004). Jupiter: The Planet, Satellites and Magnetosphere. Cambridge University Press. pp. 263–280. ISBN 978-0-521-81808-7.
  9. Pilcher, Frederick; Mottola, Stefano; Denk, Tilmann (2012). "Photometric lightcurve and rotation period of Himalia (Jupiter VI)". Icarus. 219 (2): 741–742. Bibcode:2012Icar..219..741P. doi:10.1016/j.icarus.2012.03.021.
  10. Rettig, T.; Walsh, Kevin; Consolmagno, Guy (2001). "Implied Evolutionary Differences of the Jovian Irregular Satellites from a BVR Color Survey". Icarus. 154 (2): 313–320. Bibcode:2001Icar..154..313R. doi:10.1006/icar.2001.6715.
  11. Chamberlain, M.; Brown, Robert H. (2004). "Near-infrared spectroscopy of Himalia". Icarus. 172 (1): 163–169. Bibcode:2004Icar..172..163C. doi:10.1016/j.icarus.2003.12.016.

Other websites[change | change source]