Comet Ison likely didn't survive its graze past the sun early this afternoon, astronomers say.

"It's not looking good for Ison in my opinion," said Phil Plait, an astronomer who writes for Slate's Bad Astronomy blog, during a Google Hangout organized by NASA Thursday.

"That's kind of my assessment too," agreed Karl Battams, an astrophysicist at the Naval Research Laboratory in Washington, D.C., who runs the NASA-funded Sungrazing Comets Project.

Images from NASA's SOHO spacecraft at 1:12 p.m. ET showed long tails that appeared as though they could be fading toward the sun, and the head of the comet was no longer visible.

By 2 p.m. ET, images from the Solar Dynamics Observatory spacecraft did not show the comet at all, to the surprise of Dean Pasnell, project scientist for SDO, who said the rocky material from the comet wouldn't be expected to evaporate that quickly.

SOHO-imate-1912UTC

An image of Comet ISON at 19:12 UTC (2:12 p.m. ET) captured by NASA's SOHO spacecraft shows only a fading tail near the sun, suggesting that the comet did not survive its closest approach to the sun at 1:37 p.m. ET. (SOHO/NASA)

"I'd like to know what happened to our half mile of material that was going around the sun."

Unfortunately, Pasnell said, the fact that the comet can't be seen even with SDO suggests that it is unlikely the remains of the comet will be visible from Earth.

Comet Ison is unique because it is the first sun-grazing comet ever observed from the Oort Cloud, a vast region of comets and debris near the edge of the solar system, far beyond the outermost planets. It is also one of the largest sun-grazing comets ever observed.

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Comet ISON