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SOLAR WIND BLASTS MERCURY: At a NASA teleconference today, researchers working with data from the Messenger spacecraft announced evidence that gusts of solar wind are penetrating Mercury's magnetic field and eroding material off the innermost planet's surface. The spacecraft has actually flown through plumes of ionized sodium escaping from weak points in Mercury's magnetosphere. Click here and scroll down to "Presenter #4" for relevant data and images.
REVERBERATIONS: A CME hit Earth's magnetic field on Sept. 26th, sparking one of the strongest magnetic storms in years. At the peak of the Kp=8 disturbance, auroras were sighted around both poles and more than half a dozen US states. Magnetic reverberations continued for more than 48 hours. Here is the view from forests of Skibotn, Norway, two days after the CME impact:
"The auroras were some of the most spectacular I have ever witnessed," says photographer Ole C. Salomonsen. "Actually it was the sickest thing I have ever seen in the sky!!"
Sky watchers at the highest latitudes should remain alert for auroras as Earth's magnetic field remains unsettled on Sept. 29th. Aurora alerts: text, voice.
September 2011 Aurora Gallery
[previous Septembers: 2010, 2009, 2008, 2007, 2006, 2005, 2004]
BIG SUNSPOT: The source of the CME that hit Earth on Sept. 26th is sunspot AR1302. Measuring more than 150,000 km from end to end, the sprawling active region is visible even without a solar telescope. Here it is among the seagulls at sunset on Sept. 27th:
Damien Vens took the picture from the beach in Koksijde, Belgium. "I used an off-the-shelf Nikon D7000 digital camera," he says. "The sunspot was an easy target." (Note to photographers: Never look at the sun through unfiltered optics such as camera viewfinders; even a low-hanging sun can be blindingly bright.)
AR1302 has quieted down since unleashing dual X-flares on Sept. 22nd and 24th. Nevertheless, NOAA forecasters estimate a 25% chance of more X-flares during the next 24 hours. Any such eruptions would be Earth-directed as the sunspot crosses the center of the solar disk. Solar flare alerts: text, voice.
more images: from James W. Young of Seaside, Oregon; from Andy Devey of Barnsley South Yorkshire; from J. Stetson and students in Hinckley, Maine; from Ali Norouzi of Karaj, Iran; from Theo Ramakers of Social Circle, GA; from Stefano Sello of Pisa, Italy; from Phil Greaves of Sydney Australia; from Stefan Plach of Stadt Wehlen, Saxony, Germany;
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 September 29, 2011 there were 1250 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.
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| ||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. |
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