As of this moment (Nov 26h), the title may not be a typo. Comet ISON, still a couple of days from closest approach, may have just disintegrated.
(6) Matthews Knight of Lowell Observatory has reported a drop in magnitude of the comet from magnitude 4.3 on November 22nd to magnitude 4.6 on November 23.96.
(7) Our own results confirm that comet ISON may be in trouble. We have completed an update of the Secular Visual Light Curve and we are showing it in Figure 1.
The comet is so close to the sun currently that it is difficult to get good instrumental readings or images. But data coming in over the past few days suggests that this already-spectacular comet suddenly changed output — and that the ices that held it together have been reduced to the point where the comet has fallen apart. If so, the glorious December displays everyone was hoping for won’t happen. Images like this one were potentially going to be visible to the naked eye:
Some of the recent imagery and videos have been excellent, including this one showing the tails of two comets (ISON and the smaller Encke that it seems to zoom past) rippling in the solar wind:
The comet will pass well within a million miles from the Sun’s “surface” — less than 1% of the Earth’s distance, and essentially within its atmosphere. Whatever remains of it will be exposed to tremendous heat, only about one-fiftieth of even Mercury’s superheated distance. For an object that was probably only a couple of kilometers across when it started out, and made largely of frozen gases and water, this is a difficult environment to survive. The comet’s only chance is that it is ripping past the Sun at more than 800,000 miles per hour (more than a million kilometers per hour) at the moment of closest approach.
I hope that it survives — though whether or not it graces our December skies, it will not be back again. Whatever is left is bound for deep space. Someday, humans will be able to follow it.
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