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SOLAR
WIND: A medium-speed (~425 km/s)
stream of solar wind is buffeting Earth's magnetic
field. The solar wind is not blowing hard enough
to ignite a full-fledged geomagnetic storm, but
it is stirring up some beautiful auroras around
the Arctic Circle. Check the realtime
aurora gallery for latest images.
M-CLASS
SOLAR FLARES: The magnetic canopy
of big sunspot AR1618 is crackling with M-class
solar flares. This image taken by NASA's Solar Dynamics
Observatory shows the extreme ultraviolet flash
from one of them, an M1.6-class flare on Nov. 20th
at 1928 UT:
This eruption, and another one like
it about 7 hours earlier, might have propelled faint
coronal mass ejections (CMEs) toward Earth. If so,
the impacts would likely commence on Nov. 23rd,
with a chance of high-latitude geomagnetic storms
following their arrival. Stay tuned for updates.
Aurora alerts:
text,
voice.
FAST-GROWING
SUNSPOT (Updated Nov. 21): Only
a few days ago, sunspot AR1618 was almost invisible.
Now it is a behemoth more than 10 times wider than
Earth. A movie from NASA's Solar Dynamics Observatory
shows the sunspot's development on Nov. 20-21:
As the sunspot evolves, so does its
intense magnetic field--and this means strong flares
are in the offing. Fast-changing magnetic fields
on the sun have a tendency to reconnect
and erupt. NOAA forecasters estimate a 70% chance
of M-class
flares and a 15% chance of X-flares
during the next 24 hours. Because of the sunspot's
nearly central location on the solar disk, any eruptions
will likely be Earth-directed. Solar
flare alerts: text,
voice.
Realtime
Space Weather Photo Gallery
INSIDE
THE SHADOW OF THE MOON: On Nov.
13/14, the Moon passed directly i front of the sun.
This arrangement, which produced a
total eclipse, cast the shadow of the Moon directly
down on northeast Australia. Using a wide-field
camera, eclipse-chaser Alan Dyer photographed the
shadow as it raced across the sky over Lakeland
Downs, Queensland. Scan the images, then read Dyer's
account of the shadow-transit below:
"This collage of wide-angle shots
shows the motion of the Moon's conical shadow,"
he explains. "At top, you can see the bottom
edge of the shadow just touching the Sun. This was
second contact and the diamond ring effect that
begins totality. The middle frame was taken near
mid-eclipse and shows the bright horizon beyond
the Moons shadow. However, the Sun is not centered
on the shadow because we were located well north
of the eclipse's center-line, where we had gone
to escape nearby clouds. The bottom frame was taken
at the end of totality as the first bit of sunlight
bursts out from behind the Moon. Notice the sun
sitting at the well-defined left edge of the Moon's
shadow. The shadow moved off to the right."
People who have experienced total
eclipses first-hand say the Moon's shadow is one
of the most amazing aspects of the experience. Its
arrival causes many birds to stop singing; a hush
descends on the landscape as the sky darkens and
the air temperature suddenly drops. The Moon's shadow
lances more than a quarter million miles across
the silent vacuum of space, and when it lands on
Earth, it seems to bring a bit of otherworldly cold
with it.
For more otherworldly images of the
eclipse, browse the gallery:
Realtime
Eclipse Photo Gallery
Realtime
Noctilucent Cloud Photo Gallery
[previous years: 2003,
2004,
2005,
2006,
2007,
2008,
2009,
2011]
