SUN-DIVING
COMET DISCOVERED: Astronomy
forums are buzzing with speculation about
newly-discovered Comet
C/2012 S1 (ISON). Currently
locatedbeyond
the orbit of Jupiter, Comet ISON is heading for a
very close
encounter with the sun next year. In Nov. 2013, it will
pass less than 0.012 AU (1.8 million km) from the solar
surface. The fierce heating it experiences then could
turn the comet into a bright naked-eye object.
(continued below)
Comet ISON photographed by E. Guido, G.
Sostero & N. Howes on Sept. 24. [more]
Much about this comet--and its ultimate
fate--remains unknown. "At this stage we're just
throwing darts at the board," says Karl Battams of the
NASA-supported
Sungrazer
Comet Project, who lays out two possibilities:
"In the best case, the comet is big,
bright, and skirts the sun next November. It would be
extremely bright -- negative magnitudes maybe -- and
naked-eye visible for observers in the Northern
Hemisphere for at least a couple of months."
"Alternately, comets can and often do
fizzle out!
Comet
Elenin springs to mind as a recent example,
but there are more famous examples of comets that got
the astronomy community seriously worked up, only to
fizzle. This is quite possibly a 'new' comet coming in
from the
Oort
cloud, meaning this could be its first-ever
encounter with the Sun. If so, with all those
icy volatiles intact
and never having been truly stressed (thermally and
gravitationally), the comet could well disrupt and
dissipate weeks or months before reaching the sun."
"Either of the above scenarios is
possible, as is anything in between," Battams says.
"There's no doubt that Comet ISON will be closely
watched. Because the comet is so far away, however, our
knowledge probably won't develop much for at least a few
more months."
Meanwhile, noted comet researcher John
Bortle has
pointed
out a curious similarity between the orbit of
Comet ISON and that of the Great Comet of 1680. "Purely
as speculation," he says, "perhaps the two bodies could
have been one a few revolutions ago."
Stay tuned for updates.