Comet ISON, a much-anticipated first-time visitor to the inner solar system, will likely survive its Thanksgiving Day encounter with the sun and become visible without binoculars or telescopes to observers on Earth in December, scientists said Wednesday.
Since its discovery in September 2012, Comet ISON has been a bit of a puzzle. At first, the comet was considered unusually bright because it was spotted by astronomers far beyond Jupiter's orbit, raising the prospect that it might be visible on Earth even in daylight.
However, later observations showed the comet was not brightening as much as predicted as it moved closer to the sun. Heating from the sun vaporizes ices in the comet's body, creating a long, glowing tail.
ANALYSIS: Comet ISON Offers Doomsday Deja Vu
Another issue was whether Comet ISON would survive its relatively close brush with the sun. On Nov. 28 -- Thanksgiving Day, as it turns out -- the comet will pass about 1 million kilometers, or about 621,000 miles, from the sun's surface. As it blasts around the sun, traveling 234 miles per second, the comet will be heated to about 5,000 degrees Fahrenheit, hot enough to vaporize rock and metals.