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EARTHSIDE QUIET: This weekend, none of the sunspots on the Earthside of the sun is actively flaring. NOAA forecasters put the odds of a significant eruption at no more than 10%. Solar flare alerts: text, voice.
FARSIDE NOT QUIET: The Earthside of the sun is quiet, but the farside is not. On March 23rd around 1300 UT, an active region in the sun's far-southern hemisphere erupted, hurling a bright coronal mass ejection (CME) over the sun's limb. The Solar and Heliospheric Observatory photographed the expanding cloud:
Update: Our earlier report that Mercury is in the path of the CME was incorrect. Newly-computed 3D models based on data from SOHO, STEREO-A and STEREO-B indicate that the CME will miss Mercury and hit Venus instead. A glancing impact is expected on March 25th. Because Venus has no global magnetic field to protect it from CMEs, the impact will likely strip a small amount of atmosphere from the planet’s cloudtops. No worries, though, because Venus has plenty of atmosphere to spare.
Realtime Space Weather Photo Gallery
THE BRIGHTNESS OF COMET PAN-STARRS: Comet Pan-STARRS is receding from the sun and dimming as it goes, yet sky watchers are seeing it better than ever as it moves into darker skies. How bright is it? University of Colorado atmospheric sciences professor Richard Keen, an expert estimator of astronomical magnitudes because of his work with lunar eclipses, has the answer:
"My best estimate for the comet's brightness is magnitude +1.9, a factor of five fainter than five days earlier," he says. "However, thanks to the increasing altitude of the comet in a somewhat darker sky, it is still just as easy to see with the naked eye - actually, a bit easier, because it's no longer buried in the trees." He had no trouble finding the comet for this picture looking over the Continental Divide on March 19th:
"The comet is easy to spot in the clear high-altitude skies of Colorado," Keen continues. "It appears to the unaided eye in the twilight sky as a slightly fuzzy star. Observers in more humid or hazier climates still might need binoculars to locate the comet."
"PanSTARRS will likely fade another magnitude or two over the next week as the moon brightens towards full on the night of the 26th," he predicts. "Then, on the 28th of March, the moon will rise a couple of hours after sunset, and the comet will become visible in a dark sky for the first time (for Northern observers). I expect it will still be of naked-eye brightness."
More: NASA video, 3D orbit, ephemeris, light curves.
Realtime Comet Photo Gallery
FIRST AURORAS OF NORTHERN SPRING: It is a well known scientific fact that equinoxes favor auroras. At this time of year, the slightest gust of solar wind can provoke bright lights around the poles. The phenomenon was in full effect Wednesday night in Sweden's Abisko National Park:
"Springtime IS aurora season here in Abisko," reports photographer and aurora tour guide Chad Blakley. "As the nights get shorter it seems like the auroras get more intense and their colours become more vivid. If we are lucky we have two more weeks of amazing aurora displays before the sun overpowers the northern lights."
"I also made a time-lapse video of the display and I was lucky enough to capture comet Pan-STARRS with the lights dancing overhead," he adds. "You can see the film here." Aurora alerts: text, voice.
Realtime Aurora Photo Gallery
Realtime Space Weather Photo Gallery
Realtime Noctilucent Cloud Photo Gallery
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