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Best Image Yet of Comet Closing in on Earth

Hartley 2 comet
IPAC-Caltech

We've been following the celestial peregrinations of a very large comet that's heading our way, and now astronomers have released the closest-yet image of the so-called Hartley-2 comet.

Hartley 2 comet
IPAC-Caltech

The comet, which is about .8 miles in diameter was roughly 2.3 astronomical units away from the sun when this image got taken (an astronomical unit is the distance between Earth and the sun). The fuzziness in the background of the image is due to dust from the solar system.

Astronomers say Hartley 2 should be visible with the naked eye on Oct. 20, when it gets within 11 million miles of the Earth. That will be the closest Hartley 2 has ever come to the Earth since its discovery. Australian Malcolm Hartley was the first to spot the comet in 1986. Astronomers say it likely was knocked off its original orbit somewhere near Jupiter, pointing it on a path toward the sun. The comet makes a circle of the sun each 6.46 years.

The photo was taken by NASA's Wide-field Infrared Survey Explorer, which was sent into Earth orbit last year on a seven month mission to gather space data.