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COMET LOVEJOY UPDATE: Matthew Knight of the Lowell Observatory and JHU-APL reports: "As of 16:30 UT on Dec. 15th, Comet Lovejoy has reached magnitude -3, possibly brighter. It is starting to saturate SOHO images even with narrow filters and shorter than normal exposure times." The comet is now brighter than Jupiter, but not quite as bright as Venus. If these developments continue apace, Comet Lovejoy could become visible to the naked eye in broad daylight before the end of Dec. 15th. See the news item below for further discussion of this possibility.
BIG COMET PLUNGES TOWARD THE SUN: Comet Lovejoy (C/2011 W3) is diving into the sun and furiously vaporizing as it approaches the stellar surface. The Solar and Heliospheric Observatory (SOHO) is recording the kamikaze plunge:
SOHO Coronagraph: movie, latest image
"This is, without any doubt, the brightest sungrazing comet that SOHO has ever seen," says Karl Battams of the Naval Research Lab in Washington DC.
The comet's nucleus, thought to be twice as wide as a football field, will skim approximately 140,000 km (1.2 solar radii) above the solar surface on Dec. 15/16. At such close range, solar heating will almost certainly destroy the comet's icy core, creating a cloud of vapor and comet dust that will reflect lots of sunlight.
"If Comet Lovejoy gets as bright as magnitude -4 or -5, there is a tiny but non-zero chance that it could become visible in the sky next to the sun," says Battams.
Indeed, something similar happened to Comet McNaught in January 2007 when it was visible in broad daylight: gallery. Standing in the shadow of a tall building to block the sun allowed the comet to be seen in blue sky nearby.
"Comet Lovejoy will be reaching perihelion (closest approach to the sun) right around sunset on Dec. 15th for people in the US East, Central, Mountain, and Pacific time zones," continues Battams. "Be alert for the comet to the left of the sun at that time." Caution: Do not look at or near the sun through unfiltered optics; focused sunlight can seriously damage your eyes.
Discovered on Dec. 2nd by amateur astronomer Terry Lovejoy of Australia, the comet is an unusually large member of the Kreutz family. Kreutz sungrazers are fragments of a single giant comet (probably the Great Comet of 1106) that broke apart back in the 12th century. SOHO sees one plunging into the sun every few days, but most are small, no more than 10 meters wide. Comet Lovejoy is at least ten times larger than usual.
Got pictures of Comet Lovejoy? Submit them here.
COMET LOVEJOY HAS A COMPANION: "Comet Lovejoy has a friend!" notes Karl Battams in his blog. "Look for it in the upper-half of this animation moving perfectly in step with Lovejoy. It's another Kreutz-group comet. This is not surprising. SOHO's Kreutz-group comets are very 'clumpy,' for want of a better word. We frequently see them arrive in pairs or sometimes trios, and the big bright ones in particular will often have a little companion comet."
GEMINID FIREBALLS: On the night of Dec. 13/14, NASA's All-Sky Meteor Network recorded 35 fireballs streaking over the southern USA. Twenty-two of them had remarkably similar orbits:
The clustered green orbits match the trajectory of near-Earth asteroid 3200 Phaethon, source of the annual Geminid meteor shower. The Geminids have been active this week as Earth passes through the asteroid's mysterious debris stream. The other, non-Geminid orbits correspond to random meteoroids. Not belonging to any organized debris stream, random meteoroids litter the inner solar system and produce a daily drizzle of "sporadic" fireballs.
NASA's fireball network, which connects multiple cameras in New Mexico, Alabama, Georgia and Tennessee, is a "smart" system. It rapidly and autonomously calculates meteoroid orbits from the fireballs it records. Another orbit diagram is just hours away; stay tuned.
more Geminids: from Fredrik Broms of Kvaløya, Norway; from Paul Martin of Omagh, Co Tyrone N.Ireland; from Salvador Aguirre of Hermosillo, Sonora, Mexico; from Mike Hankey of Freeland, Maryland; from Ugur Ikizler of Kirazlı - Uludag - Bursa / Turkey
CURIOSITY AND THE SOLAR STORM: Last month, a massive solar storm launched itself toward Mars just as NASA's new rover, Curiosity, was blasting off from Cape Canaveral in the same direction. Researchers say it was a welcome coincidence. For the first time in Mars-rover history, Curiosity is equipped to study solar storms, and it will be monitoring space weather all the way to the Red Planet. [full story]
Dec. 10th Total Lunar Eclipse Gallery