Image
© Juan Carlos CasadaComet ISON seen from Gran Canaria at dawn, 21 November 2013. Visible at lower left is Mercury.
Comet ISON is hurtling toward the sun today at 240,000 mph and, despite the rising heat, the comet appears to be intact. Yesterday, reports of fading spectral lines from the comet's core raised concerns that the icy nucleus might be disintegrating. Current images from NASA and ESA spacecraft, however, show the comet still going strong. Comet ISON has just entered the field of view of the Solar and Heliospheric Observatory (SOHO):


The comet's entrance coincides with a bright CME racing away from the sun's southwestern limb. Astronomers have been wondering what might happen if a CME strikes Comet ISON. This CME, however, will probably miss. The source of the cloud is a farside active region, which is not directly facing the comet.

NASA's STEREO-A spacecraft is also monitoring the comet.


"I will admit that I was pretty worried yesterday morning when reports of lower production rates came in," says Matthew Knight of the Lowell Observatory and NASA's Comet ISON Observation Campaign. "However, the STEREO-A brightness has increased steadily over the subsequent 36 hr, and I'm more optimistic again. My off-the-cuff thought is that there was an [outburst of dust, which dampened the emission lines] from roughly Nov 20-22, and it has returned to brightening again."

Astronomer Karl Battams of NASA's Comet ISON Observing Campaign urges readers to remember the following: "Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just days from perihelion has never been studied in this kind of detail - we're breaking new ground! When we factor in your standard 'comets are unpredictable' disclaimer, what we have is a huge recipe for the unknown."