Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.arcetri.astro.it/~palla/ANDREAIMMAGINI/sistemasolare/Giove/CD/Io_transit.txt Дата изменения: Mon Dec 23 15:56:41 2002 Дата индексирования: Sat Dec 22 14:38:46 2007 Кодировка:

Jupiter's 4 largest satellites have fascinated Earthlings ever since
Galileo Galilei discovered them in 1610 in one of his first astronomical
uses of the telescope. The images that will be released over the
next several days capture each of the 4 Galilean satellites in
their orbits around the giant planet.
This true color composite frame, made from narrow angle
images taken on December 12, 2000 around 15 hours UTC (spacecraft
event time) captures the innermost Galilean satellite, Io, and
its shadow in transit again the disk of Jupiter. The distance
of the spacecraft from Jupiter was 19.5 million km; the spacecraft
latitude was 3 degrees above Jupiter's equator plane. The image
scale is 117 km/pixel.
The entire body of Moon-sized Io is periodically flexed as it
speeds around Jupiter and feels, as a result of its non-circular orbit,
the periodically changing gravitational pull of the planet. The heat
arising in Io's interior from this continual flexure makes it the most
volcanically active body in the solar system, with more than 100 active
volcanoes and plumes, like giant mushroom clouds, extending 100's of
kilometers high. The white and reddish colors on its surface are due
to the presence of different sulfurous materials; the black areas
are silicate rocks.
Credit: NASA/JPL/University of Arizona
Released: December 20, 2000