STOCKHOLM (AP) — Once billed as the comet of the century, Comet ISON apparently was no match for the sun.

Images from NASA spacecraft showed the comet approaching for a slingshot around the sun on Thursday, but nothing coming out on the other side.

"It does seem like Comet ISON probably hasn't survived this journey," U.S. Navy solar researcher Karl Battams said in a Google+ hangout.

Phil Plait, an astronomer who runs the "Bad Astronomy" blog, agreed, saying "I don't think the comet made it."

Still, he said, it wouldn't be all bad news if the 4.5-billion-year-old space rock broke up into pieces, because astronomers might be able to study them and learn more about comets.

"This is a time capsule looking back at the birth of the solar system," he said.

The comet was two-thirds of a mile wide as it got within 1 million miles (1.6 million kilometers) of the sun, which in space terms basically means grazing it.

NASA solar physicist Alex Young said it would take a few hours to confirm ISON's demise, but admitted things were not looking good.

He said the comet had been expected to show up in images from the Solar Dynamics Observatory spacecraft at around noon eastern time (1700 GMT), but almost four hours later there was "no sign of it whatsoever."

"Maybe over the last couple of days it's been breaking up," Young told The Associated Press. "The nucleus could have been gone a day or so ago."

Comet ISON was first spotted by a Russian telescope in September last year.

Some sky gazers speculated early on that it might become the comet of the century because of its brightness, although expectations dimmed as it got closer to the sun.

Made up of loosely packed ice and dirt, it was essentially a dirty snowball from the Oort cloud, an area of comets and debris on the fringes of the solar system.

Two years ago, a smaller comet, Lovejoy, grazed the sun and survived, but fell apart a couple of days later.

"That's why we expected that maybe this one would make it because it was 10 times the size," Young said.

It may be a while before there's a sun-grazer of the same size, he said.

"They are pretty rare," Young said. "So we might not see one maybe even in our lifetime."

Also on HuffPost:

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  • This new view of Comet C/2012 S1 (ISON) was taken with the TRAPPIST national telescope at ESO's La Silla Observatory on the morning of Friday 15 November 2013. Comet ISON was first spotted in our skies in September 2012, and will make its closest approach to the Sun in late November 2013.

  • <a href="http://www.isoncampaign.org/potw-nov18" target="_blank"> Waldemar Skorupa (Kahler Asten, Germany)</a>

  • And another

  • The view from Italy

  • Maximilian Teodorescu

  • "Taken by Kosmas Gazeas on November 18, 2013 @ University of Athens Observatory, Athens, Greece, remotely controlled from ...Netherlands!"

  • <a href="http://spaceweather.com/" target="_blank">Michael Jäger of Ebenwaldhöhe, Austria</a>: "Whatever exploded from the comet's core also created a spectacularly-long tail, more than 16 million kilometers from end to end."

  • <a href="http://www.flickr.com/photos/hiroc/10908164844/sizes/l/">Hisayoshi Kato</a>: "the comet after the outburst on November 14, 2013. North is up, and East is to the left."

  • This graphic shows the expected location of the comet named C/2012 S1 (ISON) on Nov. 28, 2013. In late November and December of 2013, it could put on a show when heating from the sun could stir up a great deal of icy and dusty material. The comet is not a threat to Earth. At the time of its closest approach to Earth, on Dec. 26, 2013, comet ISON will come no closer than 40 million miles. When considering Earthly endeavors, that's not exactly a ringside seat.

  • Comet ISON on April 10, 2013

    Hubble's view of Comet ISON (C/2012 S1) on April 10, 2013. This image was taken in visible light. The blue false color was added to bring out details in the comet structure

  • Comet Ison Roars Through Leo

    In the early morning of Oct. 25 (6:45 a.m. EDT), NASA's Marshall Space Flight Center in Huntsville, Ala., used a 14" telescope to capture this image of Comet C/2012 S1 (ISON), which is brightening as it approaches the sun. The comet shines with a faint green color just to the left of center. The diagonal streak right of center was caused by the Italian SkyMed-2 satellite passing though the field of view. At magnitude 8.5, the comet is still too faint for the unaided eye or small binoculars, but it's an easy target in a small telescope. At this time of this image, ISON was located in the constellation of Leo the Lion, some 132 million miles from Earth and heading in toward the sun at 87,900 miles per hour.

  • NASA’s Hubble: Galaxies, Comets, and Stars! Oh My!

    Approaching the sun, Comet ISON floats against a seemingly infinite backdrop of numerous galaxies and a handful of foreground stars. The icy visitor, with its long gossamer tail, appears to be swimming like a tadpole through a deep pond of celestial wonders. In reality, the comet is much, much closer. The nearest star to the sun is over 60,000 times farther away, and the nearest large galaxy to the Milky Way is over thirty billion times more distant. These vast dimensions are lost in this deep space Hubble exposure that visually combines our view of the universe from the very nearby to the extraordinarily far away. In this composite image, background stars and galaxies were separately photographed in red and yellow-green light. Because the comet moved between exposures relative to the background objects, its appearance was blurred. The blurred comet photo was replaced with a single, black-and-white exposure. The images were taken with the Wide Field Camera 3 on April 30, 2013. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy Inc., in Washington, D.C.

  • NASA's Hubble Sees Comet ISON Intact

    A new image of the sunward plunging comet ISON suggests that the comet is intact despite some predictions that the fragile icy nucleus might disintegrate as the sun warms it. The comet will pass closest to the sun on Nov. 28. In this NASA Hubble Space Telescope image taken on Oct. 9, the comet's solid nucleus is unresolved because it is so small. If the nucleus broke apart then Hubble would have likely seen evidence for multiple fragments. Moreover, the coma or head surrounding the comet's nucleus is symmetric and smooth. This would probably not be the case if clusters of smaller fragments were flying along. A polar jet of dust first seen in Hubble images taken in April is no longer visible and may have turned off. This color composite image was assembled using two filters. The comet's coma appears cyan, a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles are pushed away from the nucleus by the pressure of sunlight. The comet was inside Mars’ orbit and 177 million miles from Earth when photographed. Comet ISON is predicted to make its closest approach to Earth on Dec. 26, at a distance of 39.9 million miles.

  • Predicted Path for Comet ISON for Late November 2013

    Predicted hour-by-hour position of Comet ISON in various instruments on one of NASA’s Solar Terrestrial Relations Observatory spacecraft between 1 a.m. EST on Nov. 26, 2013, and 7 p.m. EST on Nov. 29, 2013. The blue field of view is from the outer coronagraph, green from the inner coronagraph, and orange from the Extreme Ultraviolet Imager

  • Comet ISON Passes Through Virgo

    Comet ISON shines in this five-minute exposure taken at NASA's Marshall Space Flight Center on Nov. 8 at 5:40 a.m. EST. The image has a field of view of roughly 1.5 degrees by 1 degree and was captured using a color CCD camera attached to a 14" telescope located at Marshall. At the time of this picture, Comet ISON was 97 million miles from Earth, heading toward a close encounter with the sun on Nov. 28. Located in the constellation of Virgo, it is now visible in a good pair of binoculars.

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  • 738138main_ISON_track

  • This photo was taken by reader Mike Davies