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Metis Adrastea Thebe..



Metis, Adrastea,

Thebe, Amalthea

Closest to Jupiter (inward of the Galilean moons) are the four small moons:




Orbit: 128,000  km from Jupiter
Orbital period: 7h 4.5min
Diameter:  40 km
Mass: 9.56e16 kg

Discovered by Synnott in 1979   (Voyager  1). Metis  lies within Jupiter’s main ring.       They may be the source  of the material comprising the ring.



Orbit: 129,000  km from Jupiter
Orbital period: 7h 9.5min
Diameter:  20 km
Mass: 1.91e16 kg

Discovered by graduate student David Jewitt (working under Danielson)       in  1979       (Voyager 1). Metis and Adrastea orbit inside the        synchronous orbit radius     and inside the         Roche limit. They may be small enough       to  avoid tidal disruption but their orbits will eventually decay. Adrastea is one of the smallest moons       in the solar system.



Orbit: 181,300  km from Jupiter
Orbital period: 7h 9.5min
Diameter: 189 km
Mass: 3.5e18 kg

Discovered by Barnard  1892 September 9       using the 36 inch (91 cm) refractor at       Lick Observatory.      Amalthea was the last  moon to be discovered by direct visual observation      (as opposed to  photography).

Jupiter's moon Amalthea

Amalthea and Himalia are  Jupiter’s       fifth and sixth largest moons;       they are about the same  size but only       1/15 the size of next larger one, Europa.

Like most of Jupiter’s moons, Amalthea rotates synchronously;        its long axis is pointed toward Jupiter.

Amalthea is the reddest object in the solar system. The reddish color  is   apparently due to       sulfur originating from Io.

Jupiter's moon Amalthea

Earlier, it was thought that  its  size and  irregular shape should imply that Amalthea is a fairly       strong, rigid body.  But measurements of it’s mass made during        Galileo’s     last orbit indicate otherwise.       It now appears that Amalthea’s  density is only about the same as water and       since it is unlikely to be  composed of ice it is most likely       a loose “rubble pile” with a lot of  empty spaces.

Like Io, Amalthea radiates more heat than it        receives from the Sun (probably due to the electrical currents      induced by  Jupiter’s magnetic



Orbit: 222,000  km from Jupiter
Orbital period: 16h 11.3min
Diameter: 100 km
Mass: 7.77e17 kg

Thebe was discovered by Stephen P. Synnott in images from the Voyager 1 space probe taken on March 5, 1979, and was initially given the provisional designation S/1979 J 2.

After its discovery by Voyager 1, Thebe was photographed by the Voyager 2 spaceprobe in 1980. However, before the Galileo spacecraft arrived at Jupiter, knowledge about it was extremely limited. Galileo imaged almost all of the surface of Thebe and helped clarify its composition

Metis Adrastea Thebe..

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