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IMPACT: A CME hit Earth's magnetic
field on Oct. 24th at approximately 1800 UT (02:00
pm EDT). Acording to analysts at the Goddard Space
Weather Lab, the impact caused a strong compression
of Earth's magnetic field, allowing solar wind to
penetrate all the way down to geosynchronous orbit
for a brief period between 19:06 UT and 19:11 UT.
Earth-orbiting spacecraft could have been directly
exposed to solar wind plasma during that time.
The impact also sparked a geomagnetic
now. Geir Øye sends this picture from Ørsta,
"The sky was brightly illuminated
by auroras this evening," says Øye. "The
picture, above, was taken at 19.20 UT [just after
the most extreme compression of the magnetosphere]."
High-latitude sky watchers should
remain alert for auroras as Earth's magnetic field
continues to reverberate from the CME impact. The
best time to look is usually during the hours around
local midnight. Aurora
CORPSE: "Doomsday Comet"
Elenin was briefly famous for inaccurate predictions
that it might hit Earth. Instead it disintegrated
as it approached the sun last month. (Doomsday canceled.)
Over the weekend, Italian astronomer Rolando Ligustri
spotted the comet's remains. It's the elongated
cloud in this Oct. 22nd photo of the star field
where Elenin would have appeared if it were still
Another team of astronomers--Ernesto
Guido, Giovanni Sostero and Nick Howes--spotted
the cloud on the same night. At first they were
skeptical. "The cloud was extremely faint and
diffuse," says Guido. "We wondered if
it might be scattered moonlight or some other transient
artifact." But when the team looked again on
Oct. 23, the cloud was still there. A two-night
animation shows that the cloud is moving just
as the original comet would have. Note:
Some readers have noticed a fast-moving streak to
the to the lower right of the debris cloud. That
is an unrelated asteroid, 2000 OJ8 (magnitude 14),
which happened to be in the field of view at the
same time as the cloud of Elenin.
More information about this discovery
and continued tracking of the "comet corpse"
may be found at the Remanzacco Observatory Astronomy
WEATHER FORECAST FOR MARS: A bright
CME blasted off the sun yesterday, Oct. 22nd, and
it appears to be heading for Mars. Analysts at the
Goddard Space Weather Lab expect the cloud to reach
the Red Planet on Oct. 26th (forecast
track). A brief discussion of what CMEs can
do to Mars follows this SOHO image of the eruption:
Mars has a unique response to solar
storms shaped by the planet's strange magnetic topology.
Unlike Earth, which has a global magnetic field,
Mars is patchily covered by dozens of "magnetic
umbrellas"--remnants of an over-arching planetary
field that decayed billions of years ago. When Mars
gets hit by a CME, the resulting magnetic storms
take place in the umbrellas. Circumstantial evidence
collected by Mars Global Surveyor in the 1990s suggests
that the tops of the umbrellas light up with bright
ultraviolet auroras during such storms. Because
the structures are distributed around the planet,
these auroras can appear even at the equator.
Mars rovers and satellites should
be alert for aurora equatoralis on Oct.
Bonus: Magnetic umbrellas
are at the heart of one of Mars's greatest
mysteries: What happened to the atmosphere?
Billions of years ago, the air on Mars was thick
enough to protect vast expanses of water on the
planet’s surface. Now, however, the atmosphere is
100 times thinner than Earth's and the surface is
bone dry. Some researchers believe that magnetic
storms in the umbrellas could rip
parcels of atmosphere away from Mars and propel
air-filled magnetic bubbles into space. In this
way, space weather could be directly responsible
for the desiccation of the Red Planet.
Potentially 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 finding new
all the time.
October 24, 2011 there were 1256
potentially hazardous asteroids.
Notes: LD means
"Lunar Distance." 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
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