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Himalia (moon)
Encyclopedia
Himalia is the largest irregular
satellite
of Jupiter
, the sixth largest overall in size, and the fifth largest in mass. (Only the four Galilean moons
of Jupiter have greater mass.) It was discovered by Charles Dillon Perrine
at the Lick Observatory
on 3 December 1904 and is named after the nymph
Himalia
, who bore three sons of Zeus
(the Greek equivalent of Jupiter).
satellite
of Jupiter
, was discovered by Charles Dillon Perrine
at the Lick Observatory
on 3 December 1904.
;
;
Himalia is Jupiter's most easily-observed small satellite; though Amalthea
is brighter, its proximity to the planet's brilliant disk makes it a far more difficult object.
Himalia
who bore three sons of Zeus
(the Greek equivalent of Jupiter). The moon did not receive its present name until 1975; before then, it was simply known as 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:
The moon was sometimes called Hestia, after the Greek goddess
, from 1955 to 1975.
, the moons orbiting between 11.4 and 13 million kilometers from Jupiter at an inclination of about 27.5°. The orbital elements are as of January 2000. They are continuously changing due to Solar
and planetary perturbations.
. Measurements by Cassini confirm a featureless spectrum
, with a slight absorption at 3 μm which could indicate the presence of water.
In 2005, Emelyanov estimated Himalia to have a mass of 4.19 kg
(GM=0.28), based on a perturbation
of Elara
on July 15, 1949. JPL's Solar System Dynamics assumes that Himalia has a mass of 6.7 (GM=0.45) with a radius of 85 km.
Himalia's density will depend on whether it has an average radius of about 67 km (geometric mean
from Cassini 2000) or a radius closer to 85 km.
In November 2000, the Cassini spacecraft, enroute to Saturn
, made a number of images 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 an elongated object with axes 150 ± 20 and 120 ± 20 km, close to the Earth-based estimations.
In February and March 2007, the New Horizons
spacecraft to Pluto made a series of images of Himalia, culminating in photos from a distance of eight million km. Again, Himalia appears only a few pixels across.
, 4 kilometres in diameter, has gone missing since its discovery in 2000. One theory is that it has crashed into Himalia, 170 kilometres in diameter, creating a faint ring. This possible ring appears as a faint streak near Himalia in images from NASA's New Horizons
mission to Pluto
. This suggests that Jupiter sometimes gains and loses small moons through collisions.
Irregular satellite
In astronomy, an irregular moon is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They are believed to have been captured by their parent planet, unlike regular satellites, which form in situ....
satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, the sixth largest overall in size, and the fifth largest in mass. (Only the four Galilean moons
Galilean moons
The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei in January 1610. They are the largest of the many moons of Jupiter and derive their names from the lovers of Zeus: Io, Europa, Ganymede and Callisto. Ganymede, Europa and Io participate in a 1:2:4 orbital resonance...
of Jupiter have greater mass.) It was discovered by Charles Dillon Perrine
Charles Dillon Perrine
Charles Dillon Perrine was an American astronomer living in Argentina.Born in Steubenville, Ohio, a son of Peter and Elizabeth McCauley Perrine, and a descendant of Daniel Perrin, "The Huguenot", he worked at Lick Observatory from 1893 to 1909 and then was director of the Argentine National...
at the Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
on 3 December 1904 and is named after the nymph
Nymph
A nymph in Greek mythology is a female minor nature deity typically associated with a particular location or landform. Different from gods, nymphs are generally regarded as divine spirits who animate nature, and are usually depicted as beautiful, young nubile maidens who love to dance and sing;...
Himalia
Himalia (mythology)
Himalia is a nymph in Greek mythology. Zeus was enamoured with her and she produced three sons with him, Spartaios, Kronios, and Kytos....
, who bore three sons of Zeus
Zeus
In the ancient Greek religion, Zeus was the "Father of Gods and men" who ruled the Olympians of Mount Olympus as a father ruled the family. He was the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and his Etruscan counterpart is Tinia.Zeus was the child of Cronus...
(the Greek equivalent of Jupiter).
Discovery
Himalia, the largest irregularIrregular satellite
In astronomy, an irregular moon is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They are believed to have been captured by their parent planet, unlike regular satellites, which form in situ....
satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, was discovered by Charles Dillon Perrine
Charles Dillon Perrine
Charles Dillon Perrine was an American astronomer living in Argentina.Born in Steubenville, Ohio, a son of Peter and Elizabeth McCauley Perrine, and a descendant of Daniel Perrin, "The Huguenot", he worked at Lick Observatory from 1893 to 1909 and then was director of the Argentine National...
at the Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
on 3 December 1904.
;
;
Himalia is Jupiter's most easily-observed small satellite; though Amalthea
Amalthea (moon)
Amalthea is the third moon of Jupiter in order of distance from the planet. It was discovered on September 9, 1892, by Edward Emerson Barnard and named after Amalthea, a nymph in Greek mythology. It is also known as '....
is brighter, its proximity to the planet's brilliant disk makes it a far more difficult object.
Name
Himalia is named after the nymphNymph
A nymph in Greek mythology is a female minor nature deity typically associated with a particular location or landform. Different from gods, nymphs are generally regarded as divine spirits who animate nature, and are usually depicted as beautiful, young nubile maidens who love to dance and sing;...
Himalia
Himalia (mythology)
Himalia is a nymph in Greek mythology. Zeus was enamoured with her and she produced three sons with him, Spartaios, Kronios, and Kytos....
who bore three sons of Zeus
Zeus
In the ancient Greek religion, Zeus was the "Father of Gods and men" who ruled the Olympians of Mount Olympus as a father ruled the family. He was the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and his Etruscan counterpart is Tinia.Zeus was the child of Cronus...
(the Greek equivalent of Jupiter). The moon did not receive its present name until 1975; before then, it was simply known as or Jupiter Satellite VI, although calls for a full name appeared shortly after its and Elara
Elara (moon)
Elara is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905. It is the eighth largest moon of Jupiter and is named after the mother by Zeus of the giant Tityus....
'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 satelliteAmalthea (moon)Amalthea is the third moon of Jupiter in order of distance from the planet. It was discovered on September 9, 1892, by Edward Emerson Barnard and named after Amalthea, a nymph in Greek mythology. It is also known as '....
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.
The moon was sometimes called Hestia, after the Greek goddess
Hestia
In Greek mythology Hestia , first daughter of Cronus and Rhea , is the virgin goddess of the hearth, architecture, and of the right ordering of domesticity and the family. She received the first offering at every sacrifice in the household. In the public domain, the hearth of the prytaneum...
, from 1955 to 1975.
Orbit
At a distance of about 11.5 million km from Jupiter, Himalia takes about 251 Earth days to complete one orbit. It is the largest member of the group that bears its nameHimalia group
The Himalia group is a group of prograde irregular satellites of Jupiter that follow similar orbits to Himalia and are thought to have a common origin.The known members of the group are :* Leda...
, the moons orbiting between 11.4 and 13 million kilometers from Jupiter at an inclination of about 27.5°. The orbital elements are as of January 2000. They are continuously changing due to Solar
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and planetary perturbations.
Physical characteristics
Himalia appears neutral (grey), like the other members of its group, with colour indices B-V=0.62, V-R= 0.4, similar to a C-type asteroidC-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
. Measurements by Cassini confirm a featureless spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
, with a slight absorption at 3 μm which could indicate the presence of water.
Mass
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
(GM=0.28), based on a perturbation
Perturbation (astronomy)
Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....
of Elara
Elara (moon)
Elara is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905. It is the eighth largest moon of Jupiter and is named after the mother by Zeus of the giant Tityus....
on July 15, 1949. JPL's Solar System Dynamics assumes that Himalia has a mass of 6.7 (GM=0.45) with a radius of 85 km.
Himalia's density will depend on whether it has an average radius of about 67 km (geometric mean
Geometric mean
The geometric mean, in mathematics, is a type of mean or average, which indicates the central tendency or typical value of a set of numbers. It is similar to the arithmetic mean, except that the numbers are multiplied and then the nth root of the resulting product is taken.For instance, the...
from Cassini 2000) or a radius closer to 85 km.
| Source | Radius km | Density g Gram The gram is a metric system unit of mass.... /cm³ | Mass kg Kilogram The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water... |
|---|---|---|---|
| Emelyanov | 67 Geometric mean The geometric mean, in mathematics, is a type of mean or average, which indicates the central tendency or typical value of a set of numbers. It is similar to the arithmetic mean, except that the numbers are multiplied and then the nth root of the resulting product is taken.For instance, the... |
3.33 | 4.19 |
| Emelyanov | 85 | 1.63 | 4.19 |
| JPL SSD | 85 | 2.6 | 6.7 |
Exploration
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
, made a number of images 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 an elongated object with axes 150 ± 20 and 120 ± 20 km, close to the Earth-based estimations.
In February and March 2007, the New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...
spacecraft to Pluto made a series of images of Himalia, culminating in photos from a distance of eight million km. Again, Himalia appears only a few pixels across.
Possible relationship with Jupiter's rings
The small moon S/2000 J 11S/2000 J 11
S/2000 J 11 was an object believed to be the second-outermost prograde irregular satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2000....
, 4 kilometres in diameter, has gone missing since its discovery in 2000. One theory is that it has crashed into Himalia, 170 kilometres in diameter, creating a faint ring. This possible ring appears as a faint streak near Himalia in images from NASA's New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...
mission to Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
. This suggests that Jupiter sometimes gains and loses small moons through collisions.
External links
- Himalia Profile by NASA's Solar System Exploration
- David Jewitt pages
- Jupiter's Known Satellites (by Scott S. SheppardScott S. SheppardScott S. Sheppard is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science. Starting as a graduate student at the Institute for Astronomy at the University of Hawaii, he was credited with the discovery of many small moons of Jupiter, Saturn, Uranus, and...
)