Comet ISON zips past Mars on journey to the sun

Comet ISON zips past Mars on journey to the sun
The Mars Reconnaissance Orbiter's early image of Comet ISON on its close approach to the Red Planet. (NASA/JPL/University of Arizona)

Red planet, meet rogue comet.

Comet ISON zipped past Mars this week on its way to a potentially suicidal encounter with the sun on Thanksgiving Day.


Scientists are unsure whether the estimated 2-mile-long comet will survive its encounter with the sun or break up on the close approach.

"Comets are the rogues of the solar system," said Paul Chodas of JPL's Near Earth Objects office. "They are notoriously hard to predict."

At its closest approach to Mars on Oct. 1, comet ISON was just .07 AU, or about 6.5 million miles, from the Red Planet. That's about six times closer than the comet will ever come to Earth, according to

The Mars Reconnaissance Orbiter was able to send back some images of comet ISON using its High Resolution Imaging Science Experiment (HiRISE) camera, but as you can see in the image above, the results are not too thrilling.

In the first set of images, captured on Sept. 29, the comet doesn't look glowy and beautiful or exhibit that telltale comet tail. Instead, it looks like a clump of white dots in the center of a slightly less dense patch of dots.

But ISON enthusiasts should not panic, said Carey Lisse, a research scientist at Johns Hopkins and the coordinator of NASA's comet ISON observing campaign.

"The comet is a little fainter than expected, but those images that were released were not taken on the closest approach," he said. "We expect the images from Oct. 1st to be bigger and brighter."

Also, HiRISE was designed to take hi-resolution images of the Martian landscape rather than imaging the sky. "It was not designed to take these kinds of images," he said. "It would take some practice and understanding to make it work perfectly."

Lisse said comet ISON will likely not be the comet of the century in the shining-brighter-than-the-moon sense, but that doesn't mean there isn't plenty to like about ISON.

"This comet has never, ever been in the inner solar system before -- so it is a 4.5-billion-year-old piece of material," he said.

He notes that 18 spacecraft are hoping to image it, including the Hubble Telescope, which should take a new image of comet ISON next week.

In the meantime, Lisse found this cool-looking animation showing how comet ISON will move through the solar system.

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