Astronomers and sky watchers around the world watched in anticipation in late November and early December as comet ISON made its close pass around the sun. The prediction was that if the comet survived its close encounter with the sun, it would be one of the brightest comets in centuries. Sadly, when the comet went behind the sun, it didn’t emerge as hoped.
Scientist's initially decaled that ISON didn’t make it out of the sun's grasp only to come back later and say that at least part of the comet may have survived. A group of scientists at the annual meeting of the American Geophysical Union this week has declared ISON dead.
The scientists say that the comet broke apart during its flyby of the sun on November 28 and emerged as a diffuse cloud of dust. That cloud of dust has now mostly dissipated they believe. The scientists observing the comet say that its relatively small size likely contributed to the disintegration near the sun. Recent observations by the MRO predict that the nucleus of ISON was 330 to 3300 feet wide. The scientists say comets with a diameter of less than 1km don't typically survive a close pass to the sun
NASA is still scanning the skies for remnants of ISON using the Hubble telescope. One reason the comet brightened after its closest pass to the sun only to dim again is believed to be because the fragment cloud of the comet stretched out as it made its closest pass to the sun and then the comet brightened as the fragments clumped up again on the other side of the sun.