Daily Suspicious0bserver's Weather Post:
September 11, 2014
What's in the sky tonight?
September 11, 2014
-A pair of CMEs is heading for Earth. The two solar storm clouds were launched on Sept. 9th and 10th by strong explosions in the magnetic canopy of sunspot AR2158. NOAA forecasters estimate a nearly 80% chance of polar geomagnetic storms on Sept. 12th when the first of the two CMEs arrives. Auroras are in the offing, possibly visible at mid-latitudes before the weekend.
-Sunspot AR2158 erupted on Sept. 10th at 17:46 UT, producing an X1.6-class solar flare. A flash of ultraviolet radiation from the explosion ionized the upper layers of Earth's atmosphere, disturbing HF radio communications for more than an hour. More importantly, the explosion hurled a CME directly toward Earth. The Solar and Heliospheric Observatory photographed the expanding cloud.
Radio emissions from shock waves at the leading edge of the CME suggest that the cloud tore through the sun's atmosphere at speeds as high as 3750 km/s. That would make this a very fast moving storm, and likely to reach Earth before the weekend. Auroras are definitely in the offing.
-The X-flare of Sept 10th caused a radio blackout on Earth. Ironically, it also caused a blast of radio noise. Radio astronomers and hams in the Americas and across the Pacific Ocean heard static roaring from the loudspeakers of their shortwave receivers. "It was absolutely howling," reports Thomas Ashcraft, who sends this 3-minute recording from his amateur radio observatory in rural New Mexico.
"This is what I heard at the onset of the flare," he explains. "By the time the flare peaked, it became almost too intense for my ears."
Advice: Listen to the sound file using stereo headphones. The two channels correspond to two radio frequencies--22 and 23 MHz.
Link: http://www.spaceweather.com/images20...shcraft_02.mp3
Radio emissions like these are caused by shock waves in the sun's atmosphere. Looking at the CME pictured in the news item above, it is easy to imagine how the fast-moving cloud would spawn shock waves in the atmosphere overlying sunspot AR2158. Those shock waves triggered plasma instabilities which, in turn, generated the shortwave radio emissions.
More radio bursts may be in the offing. Sunspots AR2157 and AR2158 have unstable magnetic fields that harboor energy for strong explosions. NOAA forecasters estimate a 40% chance of X-class flares and a whopping 85% chance of M-flares on Sept. 11th.
Astro Picture of the Day:
September 11, 2014
Source:
You might not guess it, but sunrise was still hours away when this nightscape was taken, a view along the eastern horizon from a remote location in Chile's Atacama desert. Stretching high into the otherwise dark, starry sky the unusually bright conical glow is sunlight though, scattered by dust along the solar system's ecliptic plane . Known as Zodiacal light, the apparition is also nicknamed the "false dawn". Near center, bright star Aldebaran and the Pleiades star cluster seem immersed in the Zodiacal light, with Orion toward the right edge of the frame. Reddish emission from NGC 1499, the California Nebula, can also be seen through the tinge of airglow along the horizon.