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Астронет: Астрономическая картинка дня Покатайтесь на лыжах на Энцеладе http://variable-stars.ru/db/msg/1174459/eng |
Credit & Copyright: Voyager Project,
NASA
Explanation:
A small inner
moon
of Saturn, Enceladus is only about 500 kilometers
in diameter.
But the cold, distant world does reflect over 90 percent
of the sunlight it receives, giving its surface about the
same reflectivity as new-fallen snow.
Seen
here in a mosaic of
Voyager 2 images from 1981,
Enceladus shows a
variety of surface features and very few impact craters -
indicating that it is an active world even though this ice moon
should have completely cooled off
long ago.
In fact the fresh, resurfaced appearance of Enceladus suggests that
an internal mechanism, perhaps driven by tidal pumping, generates
heat and supplies liquid water to geysers
or water volcanos.
Since Enceladus orbits within the tenuous outer
E
ring of Saturn,
the moon's surface may be kept snow-bright as it is continuously
bombarded with icy ring particles.
Eruptions
on Enceladus itself would in turn supply material to the E ring.
Interplanetary
ski bums take
note: tiny Enceladus has only about one
hundredth the surface gravity of
planet Earth.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.