科学美国人60秒:Say I Saw ISON

Right this moment, a massive ball of ice and dust is careening toward the sun. Comet ISON has flared so bright in recent days that it’s now visible with the naked eye. And the comet will likely keep getting brighter until November 28th, when it dives closest to the sun, coming within just three solar radii of the sun’s surface.  

If ISON survives this Thanksgiving Day encounter, it could make for some truly spectacular sky-watching. There’s a small chance it could even be faintly visible in daylight. But such views would be dashed if the comet’s ice core disintegrates from the sun’s intense rays and gravitational force.

The rare comet was discovered last September. ISON started its journey thousands of years ago in the Oort Cloud, a spherical collection of icy bodies about one light-year from the sun.

The comet now appears as a faint smudge in the eastern sky before dawn. Its tail has noticeably lengthened, and is now almost as wide across the sky as the bowl of the Big Dipper. So grab a telescope or binoculars, or just look up: don’t miss this once-in-many-lifetimes event.

—Clara Moskowitz