[meteorite-list] Newfound Comet Could Look Spectacular in 2013 (C/2012 S1 ISON)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 26 Sep 2012 13:41:09 -0700 (PDT)
Message-ID: <201209262041.q8QKf9eR005986_at_zagami.jpl.nasa.gov>


Newfound Comet Could Look Spectacular in 2013
by Joe Rao
25 September 2012

A newly discovered comet has the potential to put on a dazzling celestial
display late next year, when it will be so bright you may be able to see it
briefly in the daytime sky.

The discovery of the object named Comet ISON was announced
Monday (Sept. 24) by Russians Vitali Nevski and Artyom Novichonok, who
detected it in photographs taken three days earlier using a 15.7-inch
(0.4-meter) reflecting telescope of the International Scientific Optical
Network (ISON), near Kislovodsk. The new comet is officially known as
C/2012 S1.

When first sighted, Comet ISON was 625 million miles (1 billion
kilometers) from Earth and 584 million miles (939 million km) from the
sun, in the dim constellation of Cancer. It was shining at magnitude 18.8
on the reverse scale used by astronomers to measure the brightness of
sky objects (the lower the number, the brighter the object). That makes
the comet currently about 100,000 times fainter than the dimmest star
that can be seen with the unaided eye.

But at its perihelion (its closest point to the sun), due on Nov. 28, 2013,
the comet will come within 800,000 miles (1.2 million km) of the sun's
surface and could evolve into a dazzling object - possibly bright enough to
be visible for a short time in broad daylight.

The fact that the orbits are so similar seems to suggest Comet ISON and the
Great Comet of 1680 could related or perhaps even the same object.

Comet ISON will be barely visible to the unaided eye when it is in the
predawn night sky, positioned against the stars of Leo in October 2013.

On Oct. 16 it will be passing very near both Mars and the bright star
Regulus - both can be used as benchmarks to sighting the comet. In November,
it could be as bright as third-magnitude when it passes very close to the
bright first-magnitude star Spica in

The few days surrounding the comet's closest approach to the sun on Nov. 28,
2013, are likely to be most interesting. It will whirl rapidly around the sun
in a hairpin-like curve and perhaps becomes a dazzlingly bright (negative-
magnitude) object.

The comet will then whirl north after perihelion and become visible during
December both in the evening sky after sunset and in the morning sky before
sunrise. Just how bright it will be and how long the tail may get during this
time frame is anybody's guess, but there is hope that it could evolve into a
memorable celestial showpiece.

And in case you haven't checked your 2013 calendar, Nov. 28 is already a
special day for those living in the United States: It is the Thanksgiving Day

Which leads to the question: Will Comet ISON be a dazzler, or a turkey?
Received on Wed 26 Sep 2012 04:41:09 PM PDT

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