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SUBSIDING METEOR OUTBURST:
Prof. Peter Brown of the University
of Western Ontario reports that "the Andromedids
are starting to fade from their peak of two days
ago." Using the Canadian Meteor Orbit Radar
Brown and colleagues have been monitoring an outburst
of Andromedid meteors numbering as many as 20 per
hour. Andromedid meteoroids come from Comet
Biela, which broke apart in the 19th century.
In recent years, Earth has been crossing through
streams of debris from the doomed comet resulting
in outbursts of meteors in 2011 and 2013. "Based
on the radar data, I'd say activity will return
to background levels later today," concludes
Brown. "The best night for sky watchers to
have seen Andromedids was probably Dec. 6-7."
COMET ISON UPDATE:
Later this month, NASA plans to
point the Hubble Space Telescope at Comet ISON to
see if anything is left of the comet after its death
plunge through the sun's atmosphere on Nov. 28th.
Note to Hubble: Don't expect to see much. Amateur
astronomers are already looking searching the comet's
position and setting hard limits on the brightness
of any remains. Consider this image taken on Dec.
8th by Eric Allen of the Observatoire du Cégep de
Trois-Rivières in Champlain, Québec:
The position of the comet--had it
survived--is circled. "I unfortunately have
to say that there is nothing that I can see down
to about magnitude +16.5, not even a small condensation,"
says Allen. More information about Allen's observing
techniques and image processing may be found here.
As Karl Battams of the Naval Research
Lab comments in his
blog on the Comet ISON Observing Campaign web
site: "The evidence appears strong that at
some point approaching perihelion Comet ISON likely
began to completely fall apart. What remains of
ISON now is going to be either just a cloud of dust,
or perhaps a few very depleted chunks of nucleus.
Either way, it's not going to flare up at this point
and we should assume the comet's show is over."
ISON Photo Gallery
AURORAS AND METEORS:
A fast stream of solar wind is buffeting Earth's
magnetic field. When the stream arrived during the
late hours of Dec. 7th, a G2-class
geomagnetic storm broke out around the poles and
Northern Lights spilled over the Canadian border
into several US states. Patrick Daigle sends this
photo from Cameron, Montana:
"Just before bedtime I checked
Spaceweather.com. That made me change my plans,"
says Daigle. "Instead of going to bed, I went
out into the cold (-24 F) in search of Northern
Lights. While I was snapping pictures, I noticed
well over a dozen shooting stars. I believe the
one pictured above is an Andromedid."
NOAA forecasters estimate a 40% chance
of additional geomagnetic storms on Dec. 9th. High-latitude
sky watchers should remain alert for auroras as
the solar wind continues to blow.
Aurora Photo Gallery
COMET LOVEJOY'S ACTIVE
TAIL: Amateur astronomers around
the northern hemisphere are reporting activity in
the tail of naked-eye Comet Lovejoy (C/2013 R1).
In Nagano, Japan, astrophotographer Kouji Ohnishi
could see big changes in less than an hour of monitoring:
Michael Jäger saw the same "disconnection
event" from his observatory in Masenberg,
Austria, on Dec. 5th. The disturbance could be caused
by a gust of solar wind or perhaps an episode of
vigorous outgassing in the comet's core.
Comet Lovejoy is now about as bright
as a 4th magnitude star. It is visible to the unaided
eye from the countryside and is an easy target for
backyard telescopes even in urban areas. Monitoring
is encouraged. Comet Lovejoy rises in the east just
before the morning sun. Sky maps:
Comet Photo Gallery
Space Weather Photo Gallery
Every night, a network
of NASA all-sky
scans the skies above the United States
for meteoritic fireballs. Automated software maintained
by NASA's Meteoroid Environment Office calculates
their orbits, velocity, penetration depth in Earth's
atmosphere and many other characteristics. Daily results
are presented here on Spaceweather.com.
On Dec. 9, 2013, the network reported
(20 sporadics, 1 Geminid, 1 sigma
In this diagram of the inner solar
system, all of the fireball orbits intersect at
a single point--Earth. The orbits are color-coded
by velocity, from slow (red) to fast (blue). [Larger
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.
December 9, 2013 there were 1445
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