Sky and Telescope - May 2012 - (Page 39)

Solar Survivor
When the comet’s head disappeared behind the occulting disks of SOHO’s coronagraphs, NASA’s Solar Dynamics Observatory (SDO) team took up the challenge of following the comet with the extreme-ultraviolet camera onboard the orbiting SDO. Its images showed the comet’s tail being violently distorted by the solar corona, looking like cigarette smoke in a turbulent breeze, just before the comet disappeared behind the solar limb. Incredibly,
Dec. 15 9:30 UT

Below: Observers around the world awaited each updated image from the coronagraphic instrument aboard the orbiting Solar and Heliospheric Observatory as Comet Lovejoy made what most people thought was its death plunge toward the Sun. But the comet survived its ﬁery encounter and emerged tailless (third image in sequence) early on December 16th, even while its pre-perihelion tail was still visible on the inbound side of the Sun. Within hours the comet grew a new tail that was far more spectacular than before.
Dec. 16 9:30 UT Dec. 16 23:54 UT
SOHO / LASCO CONSORTIUM (4)

Dec. 15 15:30 UT

Sk yandTelescope.com May 2012 39

NASA / SOLAR DYNAMICS OBSERVATORY / STEELE HILL

A new rush of excitement met the ﬁrst glimmers of Comet Lovejoy when it entered into the ﬁeld of view of the STEREO/SECCHI A and B spacecraft on December 12th and then SOHO’s C3 coronagraphic instrument on December 14th. At about 14:00 Universal Time on the 14th, the comet’s brightness in SOHO images seemed close to magnitude +1, making it several magnitudes brighter than most of the larger pygmy sungrazers seen similar at solar distances. A scant two hours later people monitoring each newly posted SOHO image were stunned to see a tiny companion traveling slightly ahead of Comet Lovejoy. And not long afterwards another comet was spotted slightly trailing the pair. But the main show was still Comet Lovejoy, which was now brightening dramatically hour by hour. Several experienced observers tried spotting the comet visually in the daytime sky, as had been done with Comet Ikeya-Seki. In New Zealand, John Drummond reported trying to see the comet when it wsa a mere 1.9° from the Sun. His eﬀorts, like those of others observers, proved fruitless. The SOHO images obtained around 4:00 UT on December 15th showed the comet was about magnitude –1 and sporting a long, bright, slightly curving dust tail. Also visible was a long but decidedly fainter tail of ionized gas, which was a bit of a surprise because an ion tail had never been positively seen on earlier pygmy sungrazers. As the time of perihelion grew near, the astronomical fraternity remained appraised of the comet’s developments in almost real-time with updates that Karl Battams posted on the SOHO Sungrazer Comet website. They included extraordinary images from spacecraft along with a running commentary on their implications. In the ﬁnal hours before perihelion on December 16.01 UT, observers around the world watched the updated SOHO images in fascination, thinking they were witnessing Comet Lovejoy’s ﬁnal death plunge.

however, the same camera soon captured images of the comet emerging from behind the Sun’s opposite limb. Comet Lovejoy had somehow survived its hellish passage through the solar atmosphere. In the hours that followed, the SOHO cameras also obtained images of the now-outbound comet’s extraordinary appearance. The old tail was visible southeast of the solar disk, still drifting sunward. To the southwest of the of the Sun, and no longer connected with the tail, stood the brilliant star-like “head” of Comet Lovejoy. At magnitude –2, or perhaps even –3, it was even brighter than it had been before perihelion! Furthermore, the comet began growing a brilliant new tail. Once again, ground-based visual attempts to see the comet in daylight failed, but it was captured in photographs, especially those taken at near-infrared wavelengths. And beginning about December 19.5 UT, amateurs in the Southern Hemisphere were photograph-

Table of Contents for the Digital Edition of Sky and Telescope - May 2012

Sky and Telescope - May 2012
Table of Contents
Spectrum
Letters
75, 50 & 25 Years Ago
News Notes
Saturn’s Raging Superstorm
Stars Above, Earth Below: Astronomy in National Parks
The Remarkable Case of Comet Lovejoy
In This Section
May’s Sky at a Glance
Binocular Highlight
Planetary Almanac
Northern Hemisphere’s Sky
Sun, Moon, and Planets
Celestial Calendar
Exploring the Solar System
Deep-Sky Wonders
Going Deep
S&T Test Report
New Product Showcase
Telescope Workshop
Planetary Imaging with Your DSLR Camera
Gallery
Focal Point

Sky and Telescope - May 2012