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POSSIBLE CME IMPACT ON MAY 17: A
coronal mass ejection (CME) hurled into space by
the X1-flare of May 15th might deliver a glancing
blow to Earth's magnetic field on May 17th. NOAA
forecasters estimate a 40% chance of polar geomagnetic
storms when the cloud arrives. High-latitude sky
watchers should be alert for auroras tonight.
Aurora alerts:
text,
voice.
M3-FLARE:
Sunspot AR1748 unleashed an M3-class solar flare
on May 17th at 0858 UT: image.
Although this is not the strongest flare we've seen
from AR1748, it could be the most geoeffective.
The sunspot is facing Earth more directly than before,
and the explosion might have hurled a CME toward
our planet. Stay tuned for updates. Solar
flare alerts: text,
voice.
To illustrate the scale of the sunspot,
photographer Göran Strand of Frösön, Sweden, inserted
Earth into a picture of AR1748 he took on May 16th:
The sunspot's primary dark cores are
nearly as big as our planet. However, that doesn't
make this a big sunspot. Other 'spots on the sun
today are larger. AR1748 is not explosive because
it is large, but rather because it has a complex
magnetic field. Lines of magnetic force twisting
above the spot are criss-crossing and re-connecting.
That's how you make an X-flare.
All by itself, AR1748 has produced
more X-flares than every other sunspot of the past
year combined. In summary, AR1748 has given us an
X1.7-class flare (0217 UT on May
13), an X2.8-class flare (1609
UT on May 13), an X3.2-class flare
(0117 UT on May 14), and an X1-class
flare (0152 on May 15). Solar
flare alerts: text,
voice.
Realtime
Space Weather Photo Gallery
DISCONNECTION EVENT
IN THE TAIL OF COMET LEMMON: Comet
Lemmon (C/2012 F6), which is receding from the sun
not far beyond the orbit of Earth, has just experienced
a "disconnection event." A cloud of dusty
plasma is propagating down the comet's tail, shown
here in a photo taken by Paul Mortfield on May 15th:
"I was pretty surprised to see
this disconnection event when I processed the images,"
says Mortfield. "The comet is a challenge to
photograph because it is so low in the sky at the
start of morning twilight."
Disconnection events can be caused
by CME impacts. A famous example is that of Comet
Encke in 2007. Comet Lemmon, however, is not
on the same side of the sun as active sunspot AR1748.
It's hard to see how the recent X-flares can be
responsible. Nevertheless, solar activity is high,
so now is a good time to monitor comet tails. They
are very sensitive to stormy space weather.
Comet Lemmon is a pre-dawn object
for observers in the northern hemisphere. It is
currently gliding alongside the Great Square of
Pegasus in the eastern sky before sunrise. The 7th-magnitude
comet is too faint to see with the naked eye, but
it is visible in medium-to-large backyard telescopes.
Observers with computerized GOTO 'scopes should
point their optics here.
More about Comet Lemmon:
3D
orbit, ephemeris,
light
curves.
Realtime
Comet Photo Gallery
Realtime
Aurora Photo Gallery
Realtime
Noctilucent Cloud Photo Gallery
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