http://spaceweather.com/ - Dec 22, 2014 12:59:22 PM - Dec 1, 2004 12:53:58 AM
384.1 16.3 Updated: Today at 2049 UT C1 1905 UT Dec22 Updated: Today at: 2000 UT3 22.3 17.6 Updated: Today at 2049 UT Updated at: 12-22-2014 12:55:04
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."
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:
458.4 8.6 Updated: Today at 1639 UT Updated: Today at: 1600 UT25.3 18.8 Updated: Today at 1639 UT
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
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.
375.8 Updated: Today at 0759 UT C8 0454 UT Dec22 0149 UT Dec22 Updated: Today at: 0800 UT Daily Sun: 22 Dec 14 Sunspots AR2241 and AR2242 have 'beta-gamma-delta' magnetic fields that harbor energy for Updated 22 Dec 2014 Update 22 Dec206 Updated 22 Dec 2014
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]
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 Arctc 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.
BURSTING COMET TO PASS BY MARS: Last week, faint Comet 15P/Finley 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/Finley 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. 222324, 25.
436.0 18.0 Updated: Today at 1919 UT C5 1301 UT Dec21 Updated: Today at: 1900 UT14.4 3.9 Updated: Today at 1919 UT Updated at: 12-21-2014 12:04:16
CME IMPACT: As expected, a coronal mass ejection (CME) hit Earth's magnetic field on Dec. 21st at approximately 1900 UT. The impact does not appear to be particularly strong. Nevertheless, polar geomagnetic storms are possible in the hours ahead.
SOLSTICE SKY ALERT: Sunday, Dec. 21st is the northern winter solstice. At 6 pm EST, the sun will reach its lowest declination in the celestial sphere, -23.5 degrees, marking the start of winter and the longest night of the year at northern latitudes. The long night could be filled with auroras. NOAA forecasters estimate a 65% chance of polar geomagnetic storms in response to glancing blows by one or two CMEs. Happy solstice!
Regular readers may remember last month's reports by Dr. Tony Phillips of radiation measurements inside commercial airplanes. During a cross-country trip between Reno, Nevada, and Washington DC, he absorbed a dose of ionizing radiation equal to about 3 dental x-rays.