On Wednesday, I reported on the approach to the Sun by Comet Lovejoy, the first "sungrazing" comet to be discovered by a ground-based observer in over 40 years. Most comet experts had predicted that the comet, officially known as C/2011 W3 (Lovejoy), would disintegrate on Friday, vaporized by its passage just a fraction of a solar radius from our star. Clearly, the comet had other ideas.
To the delight of astronomers, it survived its close encounter with the Sun, retaining much of its brilliance as seen in images from spaceborne observatories. It’s now receding from the Sun and should become visible in the night sky within days for observers at southerly latitudes.
Yesterday, as seen in images from the Solar and Heliospheric Observatory (SOHO), Comet Lovejoy rapidly closed in on the Sun, brightening (as evidenced by the "wings" on either side of the comet’s head—an artifact due to "pixel blooming" as the camera’s CCD censors became oversaturated by the comet’s brilliance, flooding adjacent pixels with brightness) and then fading in its final approach to the Sun.
Soon after Australian amateur astronomer Terry Lovejoy discovered a comet in an automated search program using a telescope equipped with a CCD detector on Nov. 27, it became clear that he had found something special.
Follow-up observations determined that the comet belonged to the Kreutz group of sungrazing comets, so called because members of this comet family—which all travel in similar orbits—pass extremely close to the Sun. The brightest Kreutz comets, such as the great comets of 1066, 1843, 1882, and 1965, have been among the most spectacular comets on record. The Kreutz group is believed to be the remnants of what was once a single, larger comet that has progressively fragmented over the past couple thousand years.
Although Lovejoy's comet—now officially known as C/2011 W3 (Lovejoy)—is not expected to rival the greatest Kreutz comets, it’s the first sungrazer to be found by a ground-based observer in over 40 years, and it should put on an impressive show online. It’s now visible in the images of several spaceborne observatories that monitor our star—the twin STEREO spacecraft and the Solar and Heliospheric Observatory (SOHO)—and should brighten as it makes what’s likely a suicidal run at the Sun.