Amalthea (moon) facts for kids
Galileo images of Amalthea
|Discovered by||E. E. Barnard|
|Discovery date||September 9, 1892|
|Shortest distance from what it orbits||181,150 km|
|Longest distance from what it orbits||182,840 km|
|Avg. distance from the center of its orbital path||181365.84 ± 0.02 km (2.54 RJ)|
|How long it takes to complete an orbit||0.49817943 ± 0.00000007 d (11 h 57 min 23 s)|
|Average speed||26.57 km/s|
|Angle above the reference plane
|0.374 ± 0.002° (to Jupiter's equator)|
|What it orbits||Jupiter|
|Size and other qualities|
|Average radius||83.5 ± 2.0 km|
|Volume||(2.43 ± 0.22)×106 km³|
|Mass||2.08 ± 0.15×1018 kg|
|Average density||0.857 ± 0.099 g/cm³|
|Surface gravity||~0.020 m/s² (~0.002 g)|
|Escape velocity||~0.058 km/s|
|Angle at which it turns
(in relation to its orbit)
|How much light it reflects||0.090 ± 0.005|
On Amalthea, Jupiter would be an amazing sight in its sky, looking 92 times bigger than the Full Moon. Amalthea is the biggest of the closer moons of Jupiter. Non-spherical and reddish in colour, it is thought to have of water ice with unknown amounts of other materials. Its surface has big craters and high mountains.
Discovery and naming
Amalthea was found on September 9, 1892 by Edward Emerson Barnard using the 36 inch (91 cm) telescope at Lick Observatory. It was the first new moon of Jupiter since Galileo Galilei's discovery of the Galilean moons in 1610.
The moon is named after the nymph Amalthea from Greek mythology who nursed the infant Zeus (the Greek equivalent of Jupiter) with goat's milk. Its Roman numeral designation is Jupiter V. The name "Amalthea" was not adopted by the IAU until 1975, although it had been in use for many decades. The name was suggested by Camille Flammarion. Before 1975, Amalthea was most commonly known simply as Jupiter V. The adjectival form of the name is Amalthean.
The surface of Amalthea is very red The reddish color may be due to sulfur coming from Io or some other non ice material. Bright patches of green appear on the major slopes of Amalthea, but the nature of this color is currently unknown. The surface of Amalthea is a bit brighter than surfaces of other closer moons of Jupiter.
How Amalthea looks from Jupiter
How Jupiter looks from Amalthea
From the surface of Amalthea, Jupiter would look enormous: it would look 92 times bigger than the Full Moon.
In 1979-1980, the Voyager 1 and 2 spacecraft made the first images of Amalthea, which resolved its surface. They also measured the moon's surface temperature. Later, the Galileo orbiter completed taking pictures of Amalthea's surface and a close flyby enabled it to constrain the moon's internal structure and composition.
Images for kids
Amalthea (moon) Facts for Kids. Kiddle Encyclopedia.