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M6-CLASS SOLAR FLARE: The magnetic canopy of sunspot AR2222 erupted today, Dec. 4th at 18:25 UT, producing an M6-class solar flare: movie. At the moment there is no sign of a CME emerging from the blast site. This preliminary conclusion could be overturned by new SOHO coronagraph data in the hours ahead, so stay tuned for updates. Solar flare alerts: text, voice
WATCH OUT FOR MOON HALOS: This week the Moon is waxing full, which means now is the time to watch out for Moon halos. Bright moonlight shining through ice crystals in the air can create a luminous network of arcs, pillars and 'dogs around the lunar disk. James Helmericks photographed this example on Dec. 3rd from the Colville River Delta in northern Alaska:
"At 3 o'clock in the morning in northern Alaska, I went out to film the Moon," says Helmericks. "At first, the Moon was surrounded by little more than a slight corona. After a while, though, all the thicker clouds departed, leaving behind a layer of high icy clouds, and we were also engulfed in thin freezing mist. When this happened a whole new set of phenomena appeared, and I snapped the picture above."
The produce such a complex display, the clouds and mist must have contained a variety of ice crystals, with many shapes and orientations. Atmospheric optics expert Les Cowley was also amazed by the brightness of the halos:
"This ice halo display would stand out if made by the sun. Made by the very much dimmer Moon 'as black as coal' it is truly remarkable," Cowley says. "The parselenic circle crossing through the Moon (only the sun makes parhelic circles) is hugely bright. Moondogs to the left and right of the Moon are intense, too. Because everything is so bright, we can see many halos that often go unnoticced. An upper tangent arc sits atop the familiar 22 degree halo. There is an outer more rare 46 degree halo. We know it is that rather than the more common supralateral arc because it does not quite touch the circumzenithal arc at the picture's top."
"The temperature was -7F with 10 knots of wind, so one needed to be bundled up to enjoy the view," adds Helmericks. That's why they call them "ice halos."
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THE RETURN OF THE EVENING STAR: For the past two months Venus has been passing behind the sun. Now the second planet is emerging from the glare, setting the stage for The Return of the Evening Star. Yesterday in Spain, the astrophotography group Project Nightflight spotted the silvery light of Venus beaming through the Atlantic sunset:
"Venus is beginning a new evening apparition," says Project Nightflight. "After sunset it is very low in the sky and sets quickly. To catch a glimpse of the Evening Star, you will need crisp skies and an unobstructed view of the western horizon. A pair of binoculars will help spot it."
"Visibility will improve during the weeks ahead," they add. "By the end of December, Venus should be plainly visible even from mid northern latitudes."
A date of particular interest is Dec. 22nd when a super-slender 2% crescent Moon will pass Venus in the evening twilight. Astrophotographers, ready your cameras!
Realtime Space Weather Photo Gallery
ELECTRIC-BLUE CLOUDS SPREADING OVER ANTARCTICA: Noctilucent clouds (NLCs) around the south pole are spreading and brightening. The latest preliminary image from NASA's AIM spacecraft shows more than 4 times the coverage of just a few days ago:
The season for southern hemisphere noctilucent clouds (NLCs) began on Nov. 22nd with just a few puffy clouds over the frozen continent. Once NLCs first appear, AIM has shown that they rapidly multiply. Indeed, this is happening now, and much of Antarctica soon could be blanketed in electric blue.
Earlier this year, AIM researchers announced a surprising teleconnection: The apparition of NLCs in the southern hemisphere is linked to cold air temperatures thousands of miles away in the northern hemisphere."For example, we found that the winter air temperature in Indianapolis, Indiana, is well correlated with the frequency of noctilucent clouds over Antarctica," says Cora Randall, AIM science team member and Chair of the Dept. of Atmospheric and Oceanic Sciences at the University of Colorado. Other US cities were similarly correlated.
Data from previous seasons show a 2-week time lag between cold outbreaks in the north and changes to NLCs in the south. However, because the 2014-2015 season is less than two weeks old, the correlation is not yet obvious. "I don't expect the northern hemisphere (NH) teleconnection signal to have significant effects on the onset of the southern hemisphere (SH) season for noctilucent clouds," says Randall. "But once planetary wave activity in the SH stratosphere is quiet (should be soon), then I would expect the connections with the NH winter to become more evident."
Randall and a group of colleagues led by Laura Holt of NorthWest Research Associates have just submitted a paper to the Geophysical Research Letters detailing the link between northern winter and southern NLCs. If you have a GRL subscription, keep an eye out for theirfuture article entitled "Summertime polar mesospheric clouds linked to wintertime surface cold air outbreaks."
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Every night, a network of NASA all-sky cameras 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. 4, 2014, the network reported 7 fireballs.
(5 sporadics, 2 sigma Hydrids)
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 image] [movies]
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 ones
all the time.
On December 4, 2014 there were 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.
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| ||3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||the underlying science of space weather |