The Moon Bites a Chunk out of the Sun
Image: The Aug. 9 X-class solar flare erupts
Living With a Star
Aug. 9, 2011 --
In April 2010, NASA's Solar Dynamics Observatory (SDO) opened its eyes for the first time. Since then, the spacecraft has revolutionized our understanding of the star on our cosmic doorstep. Through the SDO's high definition view of the sun, solar mysteries have been solved and new mysteries have been revealed for the first time. Today, as the sun ramps up in activity -- fast approaching solar maximum, predicted to occur in 2013 -- our nearest star has generated the largest explosive event since 2006: an X-class solar flare. The "X7" flare reverberated through the inner solar system, causing a storm of high-energy protons to buzz around our planet, drenching our upper atmosphere in X-rays. Even though the flare was directed away from Earth, its impact was felt. To commemorate the most energetic flare in five years, Discovery News has teamed up with Camilla Corona SDO (the SDO's famous mission mascot) to collect some of the SDO's most breathtaking photographs of the past few months.
First Light On April 21, 2010, the first photographs from the SDO were received. One of the iconic first views of the high-definition sun was that of a rising prominence; an arc of solar plasma slowly rising into the sun's hot corona.
Valentines Flare Late on Feb. 14, 2011, while the world celebrated the final hours of Valentines Day, the sun let rip with Solar Cycle 24's first X-class solar flare. At the time, the X2 blast was the biggest since the previous cycle's X9 flare in Dec. 2006.
View Blocked The nature of the SDO's orbit around the Earth means it rarely has its view of the sun interrupted. But occasionally, an unavoidable celestial event causes a break in solar observing service. This partial solar eclipse, as witnessed on July 10, 2010, was the first eclipse experienced by the SDO. Note the edges of the moon's shadow across the sun's disk -- lunar mountains and valleys are silhouetted.
Prominence Rains Down On Feb. 24, 2011, the SDO zoomed in on an M-class flare (a "medium-sized" eruption) to see a vast amount of solar plasma rain back down toward the solar "surface" -- the photosphere.
Comet Death Comets often take a death-plunge deep into the solar corona, ultimately getting snuffed out of existence by the searing heat of the sun. Now we have an incredibly powerful solar observatory looking deep into the corona, we can see these "dirty snowballs" pay the ultimate price.
Coronal Rain What goes on deep in the sun's corona often stays deep in the sun's corona. Until now. With the help of the SDO, solar scientists are able to spot tiny dynamic features in the lowermost regions of the sun's atmosphere. One phenomenon characterized by the SDO is "coronal rain" -- blobs of hot solar plasma "raining" down onto the solar surface. Oh, and that black filament thing sitting in the center of the image? That's just a piece of fluff that stowed away with the SDO before it was launched, forever stuck in the telescope's lens.
Sunspots Sunspots are blemishes seen on the sun's surface. They are the side effect of the tangled magnetic fields from the solar interior getting forced through the sun's photosphere. As the hotter plasma above the photosphere is pushed away, the cooler interior is exposed, producing a dark spot. Sunspots are immensely detailed and the SDO can peer right into them, showing intricate plasma flows and magnetic structures. The pixelated textures surrounding this sunspot group is known as granulation -- regions where plasma up-wells from the solar interior and sinks again, like the convection of boiling water in a saucepan.
Twisting Prominence On March 19, 2011, a beautiful, twisting prominence erupted into space from the solar limb. The incredible detail of the hot solar plasma wrapped in a coiled magnetic field was easily captured as the arc expanded.
An Epic Event On June 7, 2011, something happened to the sun. This "something" baffled solar physicists. This "something" had never been seen before. During a "medium" M-class solar flare, a huge quantity of solar material was kicked into space, but most couldn't escape the sun's gravitational pull. The result was a dense, dark, "giant clod of dirt" that obscured the solar disk. A coronal mass ejection (CME) was also generated, but this fascinating eruption was notable for the strangeness of the imagery captured by the SDO.
On July 26, NASA’s Solar Dynamics Observatory (SDO) noticed something peculiar about its normally uninterrupted view of the sun — a chunk was missing. But never fear, a black hole didn’t just show up swallowing some of our nearest star’s superhot plasma, it was just the moon photobombing the sun’s portrait.
The SDO has been continuously watching the sun since 2009. The high-definition space observatory orbits the Earth in a very special way that our planet rarely slips into shot (though, occasionally, even that happens during “eclipse season”). The moon, however, is a more regular visitor in the SDO’s observations. Approximately twice a year, the moon’s orbit around the Earth causes it to drift in front of the sun creating a lunar transit.
As can be seen from this transit, the edge of the moon is very sharp and defined as our planet’s only natural satellite has no atmosphere. Compare this to when the Earth blocks the solar view and you can see the hazy upper atmosphere allowing some of the brightest active regions penetrate.
The sun seen through 2 filters (304A and 171) and a blended view of both (right). NASA/SDO