This morning the website [www.spaceweather.com] published an update about Comet ISON which is hurtling toward the Sun at 238,000 km per hour:
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). See the image above.
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.
A movie obtained with the IRAM telescope in Spain recorded fading emission lines from the comet’s core. Although ‘puffs’ of material can be seen billowing down the comet’s tail, the comet itself does not appear to be disintegrating. So what caused the fade…?
“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 November 20 to 22nd, 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 the standard ‘comets are unpredictable’ disclaimer, what we have is a huge recipe for the unknown.”