CLOSE ENCOUNTER: Comet
Lulin is having a close encounter with Zubenelgenubi,
a naked-eye double star in the constellation Libra. Zubenelgenubi
is not only fun to say (zuBEN-el-JA-newbee), but also a
handy guide to the comet. Point your binoculars at the star and
voilà!--Lulin materializes in the field of view. The best time to
look is just before dawn on Friday, Feb 6th: sky
Jeff Greenwald of Laramie, Wyoming; from
James Champagne of Ramah, Louisiana; from
John Stetson of Portland, Maine; from
Becky Ramotowski of Tijeras, New Mexico;
On Feb. 4th, a team of Italian astronomers
witnessed "an intriguing phenomenon in Comet Lulin's tail."
Team leader Ernesto Guido explains: "We photographed the comet
using a remotely-controlled telescope in New Mexico, and our images
clearly showed a disconnection event. While we were looking, part
of the comet's plasma tail was torn away."
Photo credit: Ernesto Guido, Giovanni Sostero &
Paul Camilleri [more]
Guido and colleagues believe the event was caused by a magnetic
disturbance in the solar wind hitting the comet. It's a plausible
hypothesis. Magnetic mini-storms in comet tails have been observed
before--most famously in 2007 when NASA's STEREO spacecraft watched
a CME crash into Comet Encke. Encke lost its tail in dramatic
fashion, much as Comet Lulin did yesterday.
Browse the gallery to view the comet's tail before,
during and after
the disconnection event:
Lulin Photo Gallery
Hunter Telescope] [sky
AURORAS: Last night, the sun's magnetic
field near Earth tipped south, opening a crack in Earth's magnetosphere
and allowing solar wind to stream inside. Promptly, the skies over
northern Russia turned green:
Aleksander Chernucho photographed the auroras from
Mt. Khibiny in Russia's Kolyskia peninsula. "I used a Nikon
D700 set to ISO 640 for this 6-second exposure," he says.
Another outbreak of Northern Lights is due on Feb.
13th or 14th when a solar wind stream flowing from a coronal hole
is due to hit Earth. The coronal hole is not yet visible from Earth,
but NASA's STEREO-B spacecraft can see it approaching over
the sun's horizon. Stay tuned for updates.
2009 Aurora Gallery
[Previous Februaries: 2008,
the Sunspot Cycle