It might not be obvious to the naked eye, but the sun is a variable star. A sensor slated for launch onboard the Solar Dynamics Observatory will probe the sun’s "sneaky variability" with better time and spectral resolution than ever before.

October 27, 2009: Every 11 years, the sun undergoes a furious upheaval. Dark sunspots burst forth from beneath the sun’s surface. Explosions as powerful as a billion atomic bombs spark intense flares of high-energy radiation. Clouds of gas big enough to swallow planets break away from the sun and billow into space. It’s a flamboyant display of stellar power.

So why can’t we see any of it? [...]

Source: Nasa Science – click here for full article

 

Today, NASA researchers announced an event that will transform our view of the Sun and super-charge the field of solar physics for many years to come.

January 23, 2009: Today, NASA researchers announced an event that will transform our view of the Sun and, in the process, super-charge the field of solar physics for many years to come.

“On February 6, 2011,” says Chris St. Cyr of the Goddard Space Flight Center, “Super Bowl XLV will be played in Arlington, Texas.”

Wait … that’s not it.

“And on the same day,” he adds, “NASA’s two STEREO spacecraft will be 180 degrees apart and will image the entire Sun for the first time in history.”

STEREO’s deployment on opposite sides of the Sun solves a problem that has vexed astronomers for centuries: At any given moment they can see only half of the stellar surface. The Sun spins on its axis once every 25 days, so over the course of a month the whole Sun does turn to face Earth, but a month is not nearly fast enough to keep track of events. Sunspots can materialize, explode, and regroup in a matter of days; coronal holes open and close; magnetic filaments stretch tight and—snap!—they explode, hurling clouds of hot gas into the solar system. [...]

Source: Nasa Science – click here for full article

Solar flares are supposed to obliterate everything in their vicinity, yet one of the most powerful flares of the past 30 years has done just the opposite, emitting a beam of pure and unbroken hydrogen atoms. Researchers think this strange event could yield vital clues to the inner workings of solar flares.

Dec. 15, 2008: Solar flares are the most powerful explosions in the solar system. Packing a punch equal to a hundred million hydrogen bombs, they obliterate everything in their immediate vicinity. Not a single atom should remain intact.

At least that’s how it’s supposed to work.

“We’ve detected a stream of perfectly intact hydrogen atoms shooting out of an X-class solar flare,” says Richard Mewaldt of Caltech. “What a surprise! These atoms could be telling us something new about what happens inside flares.”

The event occurred on Dec. 5, 2006. A large sunspot rounded the sun’s eastern limb and with little warning it exploded. On the “Richter scale” of flares, which ranks X1 as a big event, the blast registered X9, making it one of the strongest flares of the past 30 years…

Source: Nasa Science – click here for full article