MessageToEagle.com - Astronomers using NASA's Spitzer Space Telescope have probably observed
strong carbon dioxide emissions from Comet ISON
ahead of its anticipated pass through the inner solar system later this year.
Images captured June 13 with Spitzer's Infrared Array Camera indicate carbon dioxide is slowly and steadily
"fizzing" away from the so-called "soda-pop comet," along with dust, in a tail about 186,400 miles (300,000
"We estimate ISON is emitting about 2.2 million pounds (1 million kilograms) of what is most likely carbon
dioxide gas and about 120 million pounds (54.4 million kilograms) of dust every day," said Carey Lisse,
leader of NASA's Comet ISON Observation Campaign and a senior research scientist at the Johns Hopkins
University Applied Physics Laboratory in Laurel, Md.
NASA’s Hubble Space Telescope provides a close-up look of Comet ISON (C/2012 S1), as photographed on April 10, when the comet was slightly closer than Jupiter’s orbit at a
distance of 386 million miles from the sun. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute),
and the Hubble Comet ISON Imaging Science Team
"Previous observations made by NASA's Hubble Space Telescope and the Swift Gamma-Ray Burst Mission and
Deep Impact spacecraft gave us only upper limits for any gas emission from ISON.
Thanks to Spitzer, we now know for sure the comet's distant activity has been powered by gas."
"These fabulous observations of ISON are unique and set the stage for more observations and discoveries
to follow as part of a comprehensive NASA campaign to observe the comet," said James L. Green, NASA's
director of planetary science in Washington.
However, the object is still very far away, its true size and density have not been determined accurately.
The comet ISON (or C/2012 S1) is less than 3 miles (4.8 kilometers) in diameter, about the size of a small
mountain, and weighs between 7 billion and 7 trillion pounds (3.2 billion and 3.2 trillion kilograms).
These images from NASA’s Spitzer Space Telescope of C/2012 S1 (Comet ISON) were
taken on June 13, when ISON was 310 million miles (about 500 million kilometers) from the sun.
Image credit: NASA/JPL-Caltech/JHUAPL/UCF
Like other comets, ISON is made of dust and frozen gases such as water, ammonia, methane and carbon dioxide,
representing some of the most important building blocks that formed planets 4.5 billion years ago.
The comet - discovered by Vitali Nevski and Artyom Novichonok on September 21, 2012 using a 40-cm (16-inch)
telescope in Russia - will pass within 724,000 miles (1.16 million kilometers) of the sun on Nov. 28.