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Science Forum Index » Astro Forum » Enceladus is a "Cosmic Graffiti Artist," Astronomers Discove
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| Andrew Yee |
 Posted: Thu Feb 08, 2007 11:26 pm |
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Media Relations
University of Virginia
Charlottesville, Virginia
Contact:
Fariss Samarrai, Senior News Officer
(434) 924-3778
Anne Verbiscer
(434) 243-8940
Feb. 8, 2007
Enceladus, A Moon of Saturn, is a "Cosmic Graffiti Artist," Astronomers
Discover
Astronomers from the University of Virginia and other institutions have
found that Enceladus, the sixth-largest moon of Saturn, is a "cosmic
graffiti artist," pelting the surfaces of at least 11 other moons of
Saturn with ice particles sprayed from its spewing surface geysers. This
ice sandblasts the other moons, creating a reflective surface that makes
them among the brightest bodies in the solar system (Enceladus, itself a
ball of mostly ice, is the single most reflective body in our solar
system).
"Enceladus' art is a work-in-progress, constantly altering the surfaces of
other moons orbiting within this moon's beautiful swirl of ice particles,"
said Anne Verbiscer, a research scientist in the astronomy department at
the University of Virginia and the study's lead investigator. "We've
dubbed Enceladus a graffiti artist because of its ability to alter the
appearance of the other moons."
A paper about her and her colleagues' findings appears in the Feb. 9 issue
of the journal Science.
The ring of ice particles Enceladus forms around Saturn is known as the
E-ring. At least 11 other moons orbit within the E-ring and are constantly
subjected to high velocity collisions with Enceladus's icy wake.
A series of geysers at Enceladus's south pole continually erupt, ejecting
ice particles, spewing a swirling wispy trail in the moon's wake and
ultimately forming a cloudy ring of ice particles. The ring is added to
over and over as Enceladus repeats its orbit. The particles may persist
for thousands of years, until they collide with one of the embedded moons,
including Enceladus as it flows through its own emissions.
"We asked ourselves why those other moons in the E-ring are so bright,
though they are not geologically active like Enceladus? The answer, we now
know, is that the other moons are being 'sand-blasted', so to speak, by
the ice particles ejected from Enceladus," Verbiscer said. "These are
physical characteristics not previously known."
Verbiscer added that Enceladus is of great interest to astrobiologists who
believe primitive microorganisms could, in theory, exist beneath the
surface of that moon because of the existence of liquid water below the
surface.
Planetary astronomers are particularly interested in Enceladus because of
its geological activity. At 314 miles in diameter, Enceladus is nearly
seven times smaller than the Earth's moon. But unlike our moon, Enceladus
is continually changing as its geysers spew ice and liquid water, the
likely result of heat and pressure deep within.
The surface of Enceladus is quite young, possibly less than 100 million
years. It is the sixth largest moon of the more than thirty known moons
that orbit Saturn. Because of its icy surface, Enceladus has the highest
albedo, or surface reflectivity of any body in the solar system.
Astronomer William Herschel discovered the moon in 1789.
The satellite's surface of ice includes smooth areas of plains, ice vents,
ridges and long lines of cracks at its south pole. The cracks are the
source of the ice plumes released from the body that escape into its
orbit, trailing and accumulating in its path, creating a highly visible
cloudy ring around Saturn.
Enceladus is named for a Roman and Greek mythological giant who was
considered responsible for volcanic fires on Mt. Etna in Sicily. "That
analogy certainly holds true with the realization that Enceladus is
geologically active and spraying ice particles out of its south pole,"
Verbiscer said. "But we've extended the gigantic influence that it has,
because of its ability to alter the appearance of its neighboring moons."
Verbiscer's co-investigators are Richard French of Wellesley College, Mark
Showalter of the SETI Institute and Paul Helfenstein of Cornell
University.
Audio:
Anne Verbiscer discusses findings on the "cosmic graffiti artist",
http://www.virginia.edu/uvapodcast/newspopup.php?submit=true&id=367
Additional Resources:
* Astronomy Department
http://www.astro.virginia.edu/
IMAGE CAPTION:
[http://www.virginia.edu/uvatoday/photoPopup.php?seq=1&id=1461]
Wispy fingers of bright, icy material reach tens of thousands of
kilometers outward from Saturn's moon Enceladus into the E-ring, while the
moon's active south polar jets continue to fire away. Photo courtesy
NASA/JPL/Space Science Institute |
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