Potential ‘Comet of the Century’: NASA satellite takes new photo

The Ultraviolet/Optical Telescope aboard NASA's Swift imaged comet ISON (center) on Jan. 30, when it was located about 3.3 degrees from the bright star Castor in the constellation Gemini. (NASA/Swift/D. Bodewits, UMCP)

NASA spacecraft Swift has captured a photo of Comet ISON. The icy wanderer is expected to attract stargazers worldwide when it swings close to the sun later this year.

“Comet ISON has the potential to be among the brightest
comets of the last 50 years, which gives us a rare opportunity to
observe its changes in great detail and over an extended
period,”
NASA’s official website quoted an astronomer with
University of Maryland at College Park (UMCP), Dennis Bodewits, who
helped obtain the new image.

The photo of Comet ISON was taken at the end of January, but
NASA unveiled it two months later.

Comet ISON was first discovered in September 2012 by two Russian
astronomers Vitali Nevski and Artyom Novichonokm who used the
International Scientific Optical Network located near the city of
Kislovodsk. The comet’s official designation is Comet C/2012
S1.

By tracking the celestial body over the last two months when
scanning for the most powerful explosions in the universe, Swift
allowed astronomers to learn new details about how large the comet
is and how fast it is spewing out gas and dust. SWIFT’s purpose was
to determine how much  ice is on the comet.

“Using images acquired over the last two months from Swift’s
Ultraviolet/Optical Telescope (UVOT), the team has made initial
estimates of the comet’s water and dust production and used them to
infer the size of its icy nucleus,”
NASA officials wrote in a
statement.

NASA’s image of the comet shows it as a bright and fuzzy white
ball. On January 29, ISON was about 670 million kilometers away
from Earth and 740 million kilometers from the sun.

Some scientists predict that ISON could be the “Comet of the
Century” as it makes its closest approach to the sun in late
November. But a recent analysis found that the comet is not
brightening as expected.

“It looks promising, but that’s all we can say for sure now.
Past comets have failed to live up to expectations once they
reached the inner solar system, and only observations over the next
few months will improve our knowledge of how ISON will
perform,”
an astronomer at Lowell Observatory and a member of
the Swift team, Matthew Knight, told NASA.

As NASA officials have explained, all comets are made of dust
and frozen gases that mix together to form a sort of “dirty
snowball” in space. Water ice in comets typically stays frozen
until the comet approaches within three times the Earth’s distance
to the sun, at which time the water ice heats up and changes
directly into gas (a process called sublimation), creating jets of
material that can make the comet brighter.

Swift’s observations revealed that Comet ISON is currently
spilling about 51 tons of dust and only about 60 kilos of water
every minute. The difference suggests that the comet is still too
far away from the sun in order to show its full potential,
scientists explain.

The main question: whether Comet ISON will live up to its
celestial hype or fizzle out in a whimper? The answer is not yet
known, but astronomers say it will become clear in the next few
months.

On the first day of October 2013 the comet will pass within 10.8
million kilometers of Mars, and may be spotted by orbiters around
the Red Planet. 

On November 28 — 58 days after swinging by Mars — Comet ISON
will make its closest approach to the sun, flying within 1.2
million kilometers of the star’s surface. Several sun-watching
observatories will be tracking the comet at that time, and ISON may
even become visible to the naked eye in the daytime sky, NASA
officials claimed.

The comet will make its closest approach to Earth on December
26, coming with 64.2 million kilometers of the planet.

Comet Hale–Bopp (C/1995 O1) was one of the most widely observed
comet of the 20th century and one of the brightest seen for many
decades. It was visible to the naked eye for a record 18 months,
twice as long as the previous record holder, the Great Comet of
1811.

NASA's Goddard Space Flight Center/Axel Mellinger

Source Article from http://rt.com/news/comet-ison-astronomer-nasa-126/

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