Joseph loves astronomy, and they have been talking about Amalthea, the third closest and fifth found moon of Jupiter, that was discovered by Edward Emerson Barnard on a day like today in 1892.
Amalthea is a moon of Jupiter. It has the third-closest orbit around Jupiter among known moons and was the fifth moon of Jupiter to be discovered, so it is also known as Jupiter V.
It is also the fifth-largest moon of Jupiter, after the four Galilean Moons.
Edward Emerson Barnard discovered the moon on 9 September 1892 and named it after Amalthea of Greek mythology. It was the last natural satellite to be discovered by direct visual observation; all later moons were discovered by photographic or digital imaging.
Amalthea is in a close orbit around Jupiter and is within the outer edge of the Amalthea Gossamer Ring, which is formed from dust ejected from its surface.
Jupiter would appear 46.5 degrees in diameter from its surface. Amalthea is the largest of the inner satellites of Jupiter and is irregularly shaped and reddish. It is thought to consist of porous water ice with unknown amounts of other materials. Its surface features include large craters and ridges.
Close range images of Amalthea were taken in 1979 by the Voyager 1 and Voyager 2 spacecraft, and in more detail by the Galileo orbiter in the 1990s.
More information: NASA
Amalthea was discovered on 9 September 1892 by Edward Emerson Barnard using the 91 cm refractor telescope at Lick Observatory.
It was the last planetary satellite to be discovered by direct visual observation, as opposed to photographically, and was the first new satellite of Jupiter since Galileo Galilei's discovery of the Galilean satellites in 1610.
Amalthea 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 formally adopted by the IAU until 1976, although it had been in informal use for many decades. The name was initially suggested by Camille Flammarion. Before 1976, Amalthea was most commonly known simply as Jupiter V.
The surface of Amalthea is very red. This colour may be due to sulphur originating from Io or some other non-ice material. Bright patches of less red tint appear on the major slopes of Amalthea, but the nature of this colour is currently unknown.
The surface of Amalthea is slightly brighter than surfaces of other inner satellites of Jupiter. There is also a substantial asymmetry between leading and trailing hemispheres: the leading hemisphere is 1.3 times brighter than the trailing one.
More information: NASA
The asymmetry is probably caused by the higher velocity and frequency of impacts on the leading hemisphere, which excavate a bright material -presumably ice- from the interior of the moon.
There are four named geological features on Amalthea: two craters and two faculae (bright spots). The faculae are located on the edge of a ridge on the anti-Jupiter side of Amalthea.
Craters are named after characters in Greek mythology associated with Zeus and Amalthea, faculae after locations in associated with Zeus.
During 1979, the unmanned Voyager 1 and Voyager 2 space probes obtained the first images of Amalthea to resolve its surface features, they also measured the visible and infrared spectra and surface temperature.
Later, the Galileo orbiter completed the imaging of Amalthea's surface. Galileo made its final satellite fly-by at a distance of approximately 244 km from Amalthea's centre at a height of about 160–170 km on 5 November 2002, permitting the moon's mass to be accurately determined, while changing Galileo's trajectory so that it would plunge into Jupiter in September 2003 at the end of its mission.
In 2006, Amalthea's orbit was refined with measurements from New Horizons.
More information: Solar Views
that man would find it difficult to move about on the surface.
The answer is to whittle it down to proper size
with terrajets and nuclear power,
using the debris to increase the size of Jupiter's moons so they,
too, can be colonized.
Fritz Zwicky
No comments:
Post a Comment