Comet Ison is going to be one of the most dramatic cosmic spectacles in years, and NASA believes that some of the dust being ejected from its tail may end up on Earth. The comet is a sungrazer, which means that it is going to pass close to the sun, and the closer it gets the brighter it will become. Last January, NASA comet watchers calculated that it is ejecting 122,000 tons of matter a minute from its tail, meaning that it is large and already very active.
Meteor expert Paul Wiegert of the University of Western Ontario has calculated that the dust from Comet Ison could create an unusual meteor shower on Earth. "For several days around January 12, 2014, Earth will pass through a stream of fine-grained debris from Comet ISON," says Wiegert. Because the particles are so small, Earth’s upper atmosphere will rapidly slow them to a stop. "Instead of burning up in a flash of light, they will drift gently down to the Earth below," he says. The dust could linger in our upper atmosphere for years, producing noctilucent clouds as long as it remains aloft.
Russian astronomers Vitali Nevski and Artyom Novichonok found the comet in Sept. 2012. It is named after their night-sky survey program, the International Scientific Optical Network.
In mid-2013 unfolds, the comet is still far away. “But for an object at such extreme distance, it is actually very bright," says Battams. The comet’s glow suggests that is spewing gas and dust from a fairly large nucleus—“in the 1 to 10 km range,” estimates Matthew Knight of the Lowell Observatory.
On Nov. 28, 2013, Ison will fly through the sun’s atmosphere little more than a million km from the stellar surface. If the comet survives–a big IF–it could emerge glowing as brightly as the Moon, briefly visible near the sun in broad daylight. The comet’s dusty tail stretching into the night sky could create a worldwide sensation. But such a display has been expected before when Comet Kohoutek, another sungrazer, passed through the solar system in 1973. The display never materialized, and we’ll have to wait until Ison is much closer to determine exactly what it’s likely to do.