The term “Comet of the Century” is bandied about by astronomers, researchers and other space boffins every twenty years or so, only to fall short and disappoint skywatchers the world over. Quite literally, fall short. While most of sky-watching’s most momentous moments occur when objects are closer to the earth, for a comet to truly put on a show worthy of the name “Comet of the Century,” it needs to get further from the earth, BUT closer to the sun. Flying closer to the sun sets the comet’s tail alight and that becomes the fiery finish that most look for when they stare at the sky.

comet ison

Comet ISON could appear a full moon

Comet ISON, making its first journey through the inner solar system, has researchers excited about its potential to dazzle, with some researchers suggesting that it could appear as large as a moving full moon.

Images taken on June 13 by NASA’s infrared Spitzer Space Telescope reveal that dust and carbon dioxide gas are streaming off Comet ISON, forming a tail about 186,400 miles (300,000 kilometers) long, researchers said. Obviously, the moon’s distance to the earth varies, but the tail of ISON measures near 80% of this distance.

“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 kg) 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.

Gas powered comets are the stuff that dreams are made of, at least for night gazers.

Hubble telescope observation

Previous observations of Comet ISON came from the Hubble telescope, Swift Gamma-Ray Burst Mission and Deep Impact spacecraft. The newest readings are thanks to NASA’s infrared Spitzer Space Telescope. “Thanks to Spitzer, we now know for sure the comet’s distant activity has been powered by gas.”

The potential “Comet of the Century,” which is about 3 miles (5 km) wide, is cruising toward a close encounter with the sun on Nov. 28, when it will skim just 724,000 miles (1.16 million km) above the solar surface. It could also strike earth before that, but that is a very remote possibility. And you can rest easy knowing that Bruce Willis is on the case if it comes down to it.

Comet prediction is a best-guess “science” and Comet ISON’s fate is not going to prove any easier to guess.

“Much of the carbon in the comet appears to be locked up in carbon dioxide ice,” Lisse said. “We will know even more in late July and August, when the comet begins to warm up near the water-ice line outside of the orbit of Mars, and we can detect the most abundant frozen gas, which is water, as it boils away from the comet.”

Either Comet ISON strikes earth killing us all, becomes the “Comet of the Century,” or just as likely, neither.