Sun-watching observatory turns 3 (pictures)

Three years ago, NASA launched the Solar Dynamics Observatory on an Atlas rocket from Cape Canaveral. Since that time, the millions of images returned have given us an unprecedented understanding of the sun.
This image is a composite of 25 images spanning the period of April 16, 2012, to April 15 this year. It uses the Solar Dynamics Observatory's atmospheric imaging assembly at a wavelength of 171 angstroms to reveal the zones on the sun where active regions are most common during this part of the solar cycle.
One of three instruments on board, the atmospheric imaging assembly creates an image of the sun every 12 seconds in 10 different wavelengths, giving detailed analyses of the sun at different temperatures over time.
The observatory continues to send images of phenomena, like solar flares and coronal mass ejections, at a rate of 150Mbps.

On Aug. 31, 2012, a long filament of solar material that had been hovering in the sun's atmosphere erupted into space. The coronal mass ejection, captured here by NASA's Solar Dynamics Observatory, traveled at more than 900 mps, causing auroras to appear on the night of September 3, 2012.
Producer Scott Wiessinger of NASA's Goddard Space Flight Center in Greenbelt, Md., created this lightened, blended version of the ejections using wavelengths of 304 and 171 angstroms.

This image was captured between March 28 and March 29. Solar plasma is tugged back and forth by competing magnetic forces. The observatory is the first instrument to provide such stunning detail of the magnetic forces at work.

This long loop was stretched until it broke apart as the powerful plasma eruption burst into space. Much of the material fell back into the sun, unable to break free of the gravitational pull.
These images from NASA's Solar Dynamics Observatory were taken in a wavelength of extreme ultraviolet light at 304 angstroms.

A series of active regions were lined up one after the other as they rotated into view between September 22 and September 24, 2012.

A long, C-class magnetic filament flare burst out from the sun on August 31, 2012, producing one of the most brilliant sights captured by the Solar Dynamics Observatory. Viewed in 304 angstroms of extreme ultraviolet light, the filament strand broke away and shot to the left, generating a beautiful aurora.

A close-up of an active region with huge loops of plasma. Earth easily could fit inside any of these loops.

The sun is seen here in three wavelengths of extreme ultraviolet light.

One of the first images taken by the observatory and still a favorite: a solar eruptive prominence as seen in extreme UV light on March 30, 2010. Earth is superimposed for a sense of scale.

Solar flares on display in extreme ultraviolet light. NASA said the resulting magnetic field lines, which were made visible by particles spinning along them, "connected and reconnected several times."

Bursts of gas jet off the sun's surface at 150,000 mph. The gas reaches temperatures of 1.7 million degrees Fahrenheit.

A mass of plasma was photographed spinning above the sun's surface for more than two days in October. Around the same time, the observatory recorded a shorter-lived eruption (near the upper-left edge of the image), which blew away into space.

Magnetic field lines and their interactions are superimposed on an extreme ultraviolet image. The field lines are most dense around active regions on the sun.

Passing between the observatory and the sun, a new moon temporarily creates a partial eclipse.

Strands of plasma erupt and create so-called "prominences," which are formed of cooler clouds of gases suspended by often unstable magnetic forces. Their eruptions are fairly common, but this one was larger and clearer than most.

The observatory documents looping arcs of plasma -- charged particles -- in profile.

This is an extreme ultraviolet image in which false colors trace varying gas temperatures. Reds trace the relatively cool temperatures (about 60,000 Kelvin, or 107,540 Fahrenheit); blues and greens are hotter (greater than 1 million Kelvin, or 1.79 million Fahrenheit).

The sun is a dense, cluttered mass with magnetically open holes that stream high-speed solar wind into space. In this image, one of these coronal holes stretches across the top half of the sun.

The observatory captured this image of a solar filament nearly 1 million kilometers in length. You can see it erupting along the lower left portion of the image.

A view of the unstable clouds of cooler gases suspended above the sun by the star's magnetic forces.
At times, these filaments erupt and burst into space, as seen here. Other times, they just fade away.

An artist's rendering of the Solar Dynamics Observatory.
The observatory is the first mission in a NASA program called Living with a Star, an initiative to better understand the relationship between the sun and the Earth and how the sun affects life on Earth.

A solar prominence began to bow out and then broke apart in a little less than four hours, as captured on March 16. The sequence was recorded in extreme ultraviolet light. A large cloud of the particles appeared to hover farther out above the surface before it faded away.