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COMET
LOVEJOY IN THE MORNING: Noted astronomer
John Bortle urges observers (especially in the southern
hemisphere) to "begin searching for Comet Lovejoy's
bright tail projecting up out of the morning twilight
beginning at dawn. The tails of some of the major
sungrazing comets have been extraordinarily
bright. Comet Lovejoy's apparition has been so
bizarre up to this point that it is difficult
to anticipate just what might happen next ... [including]
the exact sort of tail it might unfurl in the morning
sky."
This just in! The
ghostly tail of Comet Lovejoy was sighted this morning
shining through the twilight glow of dawn over Australia.
Peter Sayers sends this picture from Devonport,
Tasmania:
"I was surprised to be able to
see Comet Lovejoy in our Tasmanian summer early
morning twilight with the waning Moon," says
Sayers. "The comet's tail was just barely naked
eye and perhaps a degree long."
The visibility of the tail could improve
in the days ahead as the comet moves away from the
sun and the background sky darkens accordingly.
Early rising sky watchers should be alert for this
rare apparition. [finder
chart]
SPIRAL
COMET TAIL: As Comet Lovejoy recedes
intact from its Dec. 16th close encounter with the
sun, researchers are pondering a mystery: What made
the comet's tail wiggle so wildly in transit through
the sun's atmosphere? The effect is clear in this
sequence of extreme UV images recorded by NASA's
STEREO-B spacecraft:
"Why the wiggles?" wonders
Karl Battams of the Naval Research Lab. "We're
not sure. There might be some kind of helical motion
going on. Perhaps we're seeing material in the tail
magnetically 'clinging' to coronal loops and moving
with them. [Coronal loops are huge loops of magnetism
that emerge from the sun's surface and thread the
sun's atmosphere.] There are other possibilities
too, and we will certainly investigate those!"
Battams notes that these images can
be combined with similar images from STEREO-A on
the other side of the sun to produce a three dimensional
picture. "When we pair these together, and
throw in the SDO images too, we should be able to
get an incredibly unique 3-D picture of how this
comet is reacting the the intense coronal heat and
magnetic loops. We are going to learn a lot."
TIANGONG
1 AND MARS: This week, China's
new space station, Tiangong 1, is making a series
of bright passes through the morning skies of North
America. On Dec. 18th, Kevin Fetter of Brockville,
Canada, caught the 8.5-metric-ton spaceship flying
past the planet Mars (video):
Tiangong 1 is unoccupied now, but
China is planning to send Taikonauts to visit the
experimental station at least once and possibly
twice in 2012. To prepare for their arrival, last
Thursday automated systems onboard Tiangong 1 began
a series of air
quality checks inside the station's 15-cubic
meter pressurized volume.
Tiangong 1 is currently about as bright
as the stars of the Big Dipper (a value that will
approximately double when future spacecraft dock
with it). To see it, check Spaceweather's Simple
Satellite Tracker or your
cell phone for local flyby times.
Dec.
10th Total Lunar Eclipse Gallery
