The Solar Dynamics Observatory observes the sun generate an X2-class solar flare (Feb. 16, 2011).NASA/SDO
Three years ago, on Feb. 11, 2010, NASA's Solar Dynamics Observatory (SDO) was launched into orbit to begin its solar odyssey. Intended to give us the most high-definition view of the sun to date, the SDO has transformed our understanding of our nearest star.
Motivated by the desire to aid efforts to understand space weather and its impact on our planet, the SDO has done a lot more. It is unraveling the mysterious nature of flares and coronal mass ejections (CMEs), and aiding solar physicists in the hunt for the underlying mechanism that heats the solar corona.
In addition to all the science, the SDO mission has been a public outreach triumph -- an achievement embodied by a little yellow chicken mascot called Camilla Corona SDO.
So, to celebrate this landmark mission, we've selected some of our our favorite SDO observations over the years.
The sun celebrated the New Year's Eve with a solar flare.NASA/SDO
On Dec. 31, 2012, as if to celebrate New Year's Eve and the dawn of the year predicted to be "solar maximum," the sun got festive by launching a beautiful flare off the solar limb. The powerful explosion sent a towering mass of plasma high into the corona, leaving a stunning cluster of coronal loops in its wake.
A series of photos captured by the SDO as the Transit of Venus progressed on June 5, 2012.NASA/SDO
On June 5, 2012, the world watched in awe as the planet Venus slowly marched across the solar disk, an event that won't happen from our perspective for over 100 years. The SDO was able to join in the transit fun too, observing its very own exoplanet transit analog for itself. Yes, for one day, the SDO was pretending to be NASA's Kepler space telescope that spends its days looking at planets transit in front of other stars.
Venus' enigmatic 'aureole' can be used to measure the temperature of the planet's upper atmosphere during the Venus Transit on June 5, 2012.NASA/SDO
During the Transit of Venus on June 5, 2012, the SDO helped astronomers to study a rare event. Just as the planet made contact with the limb of the sun, sunlight was diffracted by the Venusian atmosphere creating a magical halo around the world. This phenomenon is known as an "aureole."
A long-lasting double flare and a coronal mass ejection erupted from the Sun over a five-hour period (Feb. 5-6, 2013). NASA/SDO
In early February, a flaring active region blasted a coronal mass ejection into space. In the process, cooler plasma from the sun's chromosphere was flung into the multi-million degree coronal plasma above. To the extreme-ultraviolet eyes of the SDO, the unfurling mass of plasma appeared dark, surrounded by a bright cluster of disturbed coronal loops. These features are often associated with prominences that appear as dark filaments on the solar disk.
An unusual ring-shaped prominence that laying flat above the sun's surface (Jan. 31, 2012)NASA/SDO
On Jan. 31, a prominence emerged from the sun. However, it was a weird prominence. "SDO observed a visual phenomena that most of us do not recall ever seeing before: a ring-shaped prominence that lay flat above the sun's surface," remarked mission scientists. The magnetic ring eventually became unstable, dumping the plasma locked inside back onto the sun.
Six images from SDO, chosen to show a representative image about every six months, track the rising level of solar activity since the mission first began to produce consistent images in May, 2010.NASA/SDO
The sun is currently ramping up in activity toward "solar maximum" in its 11-year solar cycle. It is predicted to peak some time in 2013. After being launched in 2010, the SDO has observed dramatic changes in the magnetic features erupting from the solar interior -- a sure sign that solar max is approaching.
Multi-million degree coronal loops populate the sun's lower corona -- a key component of the sun's atmospheric heating phenomenon.NASA/SDO
The sun's atmosphere -- or corona -- is many times hotter than the solar surface, a conundrum that has vexed scientists for decades. Now solar astronomers believe they have an answer. Powerful plasma waves propagating through coronal loops in the lower corona (pictured here) are resonating with the coronal plasma, heating to millions of degrees. Science from the SDO has found evidence for these waves, boosting the viability of this coronal heating mechanism.
A solar prominance creates an optical illusion in the sun's atmosphere.NASA/SDO
What the heck is that? The Death Star is suckling on the sun!
No it's not. That's a "hole" carved out by the magnetic field of a prominence, forming a dark patch in the multi-million degree coronal plasma. Sorry conspiracy theorists.
A mass of plasma at the very top of the sun rose up from the surface, streamed along, darted back and forth, and finally rose up and broke away into space (Nov. 19-21, 2012).NASA/SDO
Like the thin high-altitude cirrus cloud you sometimes see at sunset, the sun also has its own wispy clouds. However, these "clouds" were launched from the sun's lower atmosphere to high above the sun's surface encased in a warped magnetic field. On Nov. 19-21, 2012, a wonderful example of this plasma "cloud" was spotted by the SDO that eventually blew into space.
NASA’s Solar Dynamics Observatory (SDO) spots an X1.1 flare through its high-definition eyes (July 2012).NASA/SDO
Early July 2012, the sun generated an impressive X1.1-class X-ray flare, saturating the SDO's camera. A dazzling optical effect was the result, creating an "X" across the EUV observation.
The view through the SDO’s AIA 131A filter, sensitive to superheated plasma of several million degrees Kelvin (Celsius) high in the sun’s corona, minutes after the flare erupted on July 12, 2012.NASA/SDO
A week later, it unleashed a more powerful X1.4-class solar flare. This time it was aimed right at us, bathing our upper atmosphere in X-ray radiation.
On Sept. 11, 2012, the SDO captured the Earth eclipsing the sun during the observatory's "eclipse season."NASA/SDO
Although the SDO's orbit was designed to insure it has an uninterrupted view of the sun, occasionally the Earth (and moon) can get in the way. This is one example of what the solar observatory sees when the sun photobombs its frame during an "eclipse season."
A massive explosion on the sun kicked up an unusual coronal mass ejection (June 2011)NASA/SDO
In June 2011, the SDO captured a very strange solar eruption. A coronal mass ejection was unleashed, but a huge amount of plasma was kicked up into the corona... and it all fell back down again.
"It looks like somebody just kicked a giant clod of dirt up into the air," remarked C. Alex Young, NASA solar physicist.
Comet Lovejoy dashes from behind the sun after a death-defying dive (Dec. 2011).NASA/SDO
The sun, generally, is not a comet's best friend. But for Comet Lovejoy that decided to play "chicken" with the gigantic mass of superheated plasma, it was the frozen ball of dirty ice that had the last laugh. In December 2011, Lovejoy made a close pass of the sun and lived to tell the tale. Other comets, alas, aren't so lucky.
The SDO takes a close-up view of a trio of sunspots in Active Region 1504, the site of seveal M-class flares in June, 2012.NASA/SDO
The SDO is also an ace sunspot tracker, adept at watching these dark features grow and multiply as the magnetic field threaded through them becomes more and more chaotic. We are currently in prime sunspot-spotting season, so keep an eye on the SDO for more incredibly detailed imagery of these complex phenomena.