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SOLAR RADIO STORM: Did you know sunspots can make noise? Consider the following: "Over the past few days, I have been recording a sustained solar radio storm at 180 MHz," reports amateur radio astronomer Thomas Ashcraft of New Mexico. "It consists of Type I radio bursts and sounds like ocean surf. Here is an audio sample from March 27th at 1930 UT. The sun seems to be entering a new phase of dynamism."
Radio emissions like these are caused by plasma instabilities in the sun's atmosphere above sunspots. With the sun becoming 'radio-active,' it's no coincidence that sunspots are emerging in abundance. Leading the way is behemoth active region AR1176, shown here in a photo taken yesterday by Larry Alvarez of Flower Mound, Texas:
AR1176, the multi-cored ensemble at the bottom of the image, is dragging a pair of long magnetic filaments behind as it cuts aross the solar disk. Two more sunspots are visible in the active region's wake. The entire starscape spans more than 500,000 km from top to bottom--truly impressive. "I call this picture Solar Rip," says Alvarez, "because it looks like a rip in the stellar surface."
With so much happening on the sun, now is a good time to consider purchasing a solar telescope. Space Weather Store offers an out of the box system that requires minimal setup or previous experience.
more images: from JP Brahic of Uzes, France; from Jim Fakatselis of Huntington, NY; from Mike Borman of Evansville, Indiana; from Rogerio Marcon of Campinas SP Brasil; from N. Pommeville and J. Stetson of South Portland, Maine; from Dave Gradwell of Birr Ireland; from Raymond Lalonde of Cornwall, Ont. Canada;
A RAINBOW AT NIGHT: Recipe for a rainbow: Add bright sunlight to raindrops and voila!--a beautiful band of multi-colors arcs across the sky. With such an ingredient list, you might suppose that rainbows can only be seen during the day, yet on March 24th Ethan Tweedie of Kamuela, Hawaii, recorded this spectacular example long after dark:
"It was a moonbow," explains Tweedie. The bright moon played the role of sun, illuminating nightime raindrops falling through the damp Hawaiian air. "I've been trying to photograph a moonbow for a long time. Last night I was driving back from the Volcano there it was!"
Tweedie's long exposure revealed something even more rare: a secondary moonbow. It's the faint 'bow arciing above the brighter primary. Primary rainbows are caused by single reflections inside raindrops; secondary bows are caused by double reflections. It was a night to remember, indeed.
March 2011 Aurora Photo Gallery
[previous Marches: 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002]