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URSID METEOR SHOWER: Today, Dec. 22nd, Earth is passing through a diffuse stream of debris from Comet 8P/Tuttle, source of the annual Ursid meteor shower. Because of winter weather, this northern shower is seldom observed, but it has produced at least two major outbursts in the past 70 years, in 1945 and 1986. Modelling by forecaster Jérémie Vaubaillon suggests a possible encounter in 2014 with a filament of comet dust, which could produce extra activity around 00h40m UT on Dec. 23rd. The nearly-new Moon on Dec. 22-23 creates perfect viewing conditions. Northern observers can expect to see 10+ meteors per hour streaming from a point not far from Polaris, the North Star. [meteor radar]
POLAR STRATOSPHERIC CLOUDS: A possible outbreak of polar stratospheric clouds (PMCs) is underway around the Arctic Circle. Unlike normal grey-white clouds, which hug Earth's surface at altitudes of only 5 to 10 km, PMCs float through the stratosphere (25 km) and they are fantastically colorful. Ivar Marthinusen sends this picture of the phenonenon from Skedsmokorset, Norway:
"Right after sunset on Dec. 22nd, the clouds were so bright they were uncomfortable to look at directly," says Marthinusen.
Also known as "nacreous" or "mother of pearl" clouds, these icy structures form in the lower stratosphere when temperatures drop to around minus 85ºC. Sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colors by diffraction and interference. Once thought to be mere curiosities, some PMCs are now known to be associated with the destruction of ozone.
"Nacreous clouds far outshine and have much more vivid colours than ordinary iridescent clouds, which are very much poor relations and seen frequently all over the world," writes atmospheric optics expert Les Cowley. "Once seen they are never forgotten."
Realtime Space Weather Photo Gallery
SOLSTICE GEOMAGNETIC STORM: A coronal mass ejection (CME) hit Earth's magnetic field on Dec. 21st, sparking a G1-class geomagnetic storm. For sky watchers around the Arctic Circle, the longest night of the year was filled with colorful lights. Truls Tiller sends this picture from Tromsdalen, Norway:
"I was just about to go to bed on Dec. 22nd when I had a feeling [that something was up]," says Tiller. "So, at 2.45 a.m., I took my camera and went into the forest just behind my house. This is what I saw. It was amazing!"
More lights are in the offing. NOAA forecasters estimate a 60% chance of continued geomagnetic storms on Dec. 22-23 as Earth passes through the wake of the CME. Aurora alerts: text, voice
Realtime Aurora Photo Gallery
BURSTING COMET TO PASS BY MARS: Last week, faint Comet 15P/Finlay exploded in brightness. You still can't see it with the naked eye, but the comet's surge from magnitude +11 to +8.7 suddenly makes it an attractive target for medium to large backyard telescopes. UK astrophotographer Damian Peach took this picture using 20-inch optics on Dec. 19th:
"There were some nice jets present following the outburst," he says.
Consider this perfect timing: The outburst occurred just as the comet is passing by Mars. On Dec. 23rd and 24th, 15P/Finlay will be 1/6th of a degree from the Red Planet. Astrophotographers interested in a photo-op can find the pair in he southwestern sky just after sunset. Sky maps: Dec. 22, 23, 24, 25.
Realtime Comet Photo Gallery
Realtime Meteor Photo Gallery
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. 22, 2014, the network reported 11 fireballs.
(6 sporadics, 2 December Leonis Minorids, 1 Quadrantid, 1 Geminid, 1 Ursid)
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 22, 2014 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters: 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.
|Asteroid || |
|2007 EJ || |
|1991 VE || |
|2004 BL86 || |
|2008 CQ || |
|2000 EE14 || |
| ||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 |