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Jupiter's moon Amalthea

Amalthea is very red

 Automatic translationAutomatic translation Category: moons
Updated June 01, 2013

Amalthea was discovered in 1892 by the American astronomer Edward Emerson Barnard using the 91 cm telescope at Lick Observatory. This is the first satellite of Jupiter discovered since the Galilean moons in 1610.
The surface of Amalthea is very red, its reflectivity increases with wavelength from the green to the infrared.
The period of revolution of Amalthea is 12 days.
The rotation around its axis is synchronous, ie, 12 days. Its surface is cratered. Its craters are very large compared to the size of Amalthea. Amalthea is made of ice and debris very porous. Pan crater, the largest, measuring 100 km in diameter and is deep at least 8 km. The crater, Gaea, measuring 80 km, it is about twice as deep as Pan. Amalthea has two mountains, and Mons Ida Mons Lyctas. Amalthea orbits Jupiter at a distance of 181,000 km. The orbit of Amalthea is very close to the outer edge of the ring Gossamer.
This ring is composed of dust ejected from the satellite.
Amalthea is not to be confused with the asteroid (113) Amalthea. Amalthea's name comes from the nymph feeds Jupiter.

 Amalthée satellite de Jupiter

Image: photo taken in 1999 by the Galileo spacecraft

Amalthea (Jupiter V)Characteristics
Dimensions262x146x134 km
Mass2,1x1018 kg
Axial tilt0
Periapsis181 150 km
Apoapsis182 840 km
Eccentricity 0.00319
Escape velocity ≈ 0.0581 km/s
Orbital period0.49817943 d
Rotation periodsynchronous
discovered date September 9, 1892
discovered byEdward Emerson Barnard

nota: November 5, 2002, the Galileo spacecraft flew past Amalthea at 160 km altitude. During the close flyby, no picture of Amalthea, was published, the only published views of the Jovian satellite fifth, lack of sharpness.

Amalthea and Métis on Gossamer


Jupiter is a failed sun, when it was formed from the Sun, the giant planet has reached a mass sufficient to generate nuclear reactions (mass = 318 times the Earth). However, Jupiter gives off more energy into space than it receives from the Sun. As rocky planets (Mercury, Venus, Earth and Mars), the four moons of Jupiter (Ganymede, Callisto, Io and Europa) have formed near her. Small irregularly shaped objects, are likely to have been captured during or after the formation of the Galilean moons.
Amalthea was seems to have formed far from the heat of Jupiter, in cold regions of the solar system. It is possible that this is an asteroid captured by the enormous gravity of Jupiter.
It is very difficult to observe the small moons of Jupiter as they are embedded in the huge luminous halo of the giant planet. The only published photos of Amalthea, are blurred.
Near-infrared light spectra of small inner satellites Amalthea as, Metis, Thebe, and others, are similar to those of asteroids, ie, D-type wavelength 2.5 micrometer.


A characteristic of deep absorption was detected at 3 micrometers in the spectra of the back of Amalthea, which corresponds to those of non-ice Callisto and can be attributed to hydrated minerals. These surface materials can not be explained, if the satellite was formed on its present orbit by accretion from the nebula circumjovian.
Amalthea, Metis and Thebe may be the remains of the building blocks, of Jupiter.

Image: This image was taken with the infrared camera IRTF facility NSFCAM.
To see the small moons close to Jupiter, a filter was used to eliminate reflections of the planet and improve the detection of small rings and inner satellites.
In the photo, the brightest satellite, Amalthea is, this moon appears above the ring Gossamer, the left edge of the image. You can see also, Métis, the small inner moon of 40 km in diameter along the border of the Gossamer ring (right in photo).

 Jupiter's rings seen in infrared

Jupiter's moons


Jupiter, the largest planet in the solar system is surrounded by more than 60 moons.
The first Jupiter's moons were discovered in 1610. Galileo Galilei discovered at that time the four largest Jovian satellites system Io, Europa, Ganymede and Callisto. These Galilean moons called from, were the first to be observed except that of the Earth. Today, thanks to space probes, we have a more comprehensive view of the Jovian system.
This is the series of Voyager missions which helped lift the veil on the Jovian system by discovering in 1979, Metis, and Thebe Adrastea. Before the space age, astronomers had discovered Amalthea (1892), Himalia (1904), Elara (1905), Pasiphae (1908), Sinope (1914), and Lysithea Carme (1938), Ananke (1951), Leda (1974 ) and Themisto (1975.
Between 1979 and 1999, no new satellite of Jupiter was discovered it was not until October 6, 1999, to Spacewatch program discovers a new moon to Jupiter, Callirrhoe.


Observations in 2000 revealed ten new moons, bringing the number of satellites to 28 after the rediscovery of Themisto, Kalyke, Jocasta, Erinome, Harpalyke, Isonoe, Praxidike, Megaclite, Taygetos Chaldene and S/2000 J 11. The following year, eleven moons were discovered, bringing the total to 39, Hermippus, Eurydome, Sponde, Kale, Autonoe, Thyone, Pasithea, Euanthe, orthoclase, and Aitne Eupora. In 2002, only one moon, Archy, was discovered.
In 2003 there discovered 23 new satellites, Eukelade, S/2003 J 2, S/2003 J 3, S/2003 J 4, S/2003 J 5, Helice, Aoede, hegemony, S/2003 J 9, S / 2003 J 10, Kallichore, S/2003 J 12, Cyllene, S/2003 J 14 S/2003 J 15 S/2003 J 16 S/2003 J 17 S/2003 J 18 S/2003 J 19 , Carpo, Mneme, Thelxinoe and S/2003 J 23. Most of the 47 satellites discovered after the 2000s are small moons of a few kilometers in diameter, the largest barely reaching 9 km.
In 2006, 63 known moons of Jupiter, the record of the solar system.

Moons of JupiterDiameter (km)Mass (kg)
Ganymede (Jupiter III)52621.5×1023
Callisto (Jupiter IV)48211.1×1023
Io (Jupiter I)36438.9x1022
Europa (Jupiter II)31224.8×1022
Amalthea (Jupiter V)262x146x1342.1x1018
Himalia (Jupiter VI)1706.7×1018
Thebe (Jupiter XIV)110x901.5x1018
Elara (Jupiter VII)868.7×1017
Pasiphae (Jupiter VIII)603.0×1017
Carme (Jupiter XI)461.3×1017
Sinope (Jupiter IX)387.5×1016
Lysithea (Jupiter X)366.3×1016
Ananke (Jupiter XII)283.0×1016
Adrastea (Jupiter XV)20x16x140.2x1016
Leda (Jupiter XIII)160.6×1016
Callirrhoe (Jupiter XVII)90.087×1016

See also

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