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SOLAR FILAMENT: An awesome,
km long filament of magnetism is stretched across
the sun's southern hemisphere. If it collapses or
erupts, as filaments often do, the result could
be an Earth-directed coronal mass ejection. Meanwhile
it is a fine target for backyard solar telescopes.
Magnetic instabilities in the filament
caused an eruption today around 1600 UT. The filament
was not destroyed, nor was material hurled toward
Earth. SDO movies: mpeg,
TO SEE COMET HARTLEY: For backyard
stargazers, the next few nights are the best time
to see green Comet 103P/Hartley 2 as it approaches
Earth for an 11-million-mile close encounter on
Oct. 20th. Set your alarm for the dark hours before
dawn, go outside, and look straight up. You will
find Hartley 2 not far from the bright star Capella:
map. Although the comet is barely visible to
the unaided eye, it is easy to find in binoculars
and looks great through a backyard telescope.
Last night, Filipe Alves of Portalegre, Portugal,
obtained the following long-exposure image using
an 8-inch telescope and a KAF-8300 refrigerated
CCD camera. It shows the comet's vast green atmosphere
and an auburn tail of dust:
Many readers have asked, why is the comet green?
Answer: Hartley 2's green color comes from the gases
that make up its Jupiter-sized atmosphere. Jets
spewing from the comet's nucleus contain cyanogen
(CN: a poisonous gas found in many comets) and diatomic
carbon (C2). Both substances glow green
when illuminated by sunlight in the near-vacuum
NASA scientists say
103P/Hartley 2 is one of the most active comets
they've seen, with copious outgassing from jets
in the nucleus. Amateur astronomers are encouraged
to monitor the action and submit their images here.
more images: from
Tom Jorgenson of Neenah, Wisconsin; from
Yandong Hu of Mt. Wawushan, Jiangsu, China;
Rolando Ligustri using a robotic telescope in
New Mexico; from
Marian Urbaník of Staškov, Slovak republic;
John Chumack of Dayton, Ohio; from
Jan Koeman of Kloetinge, the Netherlands; from
Jodi and Roy McCullough of Salem Ohio; from
Mike Broussard of Maurice, Louisiana; from
Mike Holloway of Van Buren, Arkansas; from
Norm Klekoda and Al Bell near Grand Rapids,
Doug Zubenel of Monument Rocks, Gove County,
Gregg Ruppel of Ellisville, Missouri
AURORAS: A surprise display of Northern
Lights spread across Greenland,
and even parts of the United
States on Oct. 17th. "There was only a
20% chance of geomagnetic activity in my area, but
the auroras took off," reports Zoltan Kenwell
who took this picture just north of Edmonton, Alberta:
5D Mark II, EF 24mm lens, f1.4, ISO 1250, 20s
"It was a cool -3C outside, but no wind,"
he says. "A beautiful night!"
The auroras were sparked by a fluctuation in the
IMF: the interplanetary
magnetic field tipped south, opening a hole in Earth's
magnetosphere. Solar wind poured in and fueled the
display. More auroras are possible on Oct. 19th
and 20th when a solar wind stream is due to brush
past Earth. Get your aurora
2010 Aurora Gallery
[previous Octobers: 2009,
Hazardous Asteroids (PHAs
are space rocks larger than approximately 100m that can come
closer to Earth than 0.05 AU. None of the known PHAs is on
a collision course with our planet, although astronomers are
all the time.
October 18, 2010 there were 1155 potentially
Notes: LD means "Lunar
1 LD = 384,401 km, the distance between Earth and the Moon.
1 LD also equals 0.00256 AU. MAG is the visual magnitude
of the asteroid on the date of closest approach.
official U.S. government space weather bureau
first place to look for information about sundogs,
pillars, rainbows and related phenomena.
call it a "Hubble for the sun." SDO is the most
advanced solar observatory ever.
views of the sun from NASA's Solar and Terrestrial
and archival images of the Sun from SOHO.
the NOAA Space Environment Center
underlying science of space weather