When a rather large M 3.6 class flare occurred near the edge of the Sun on Feb. 24, 2011, it blew out a gorgeous, waving mass of erupting plasma that swirled and twisted for 90 minutes. NASA’s Solar Dynamics Observatory captured the event in extreme ultraviolet light. Because SDO images are high definition, the team was able to zoom in on the flare and still see exquisite details. And using a cadence of a frame taken every 24 seconds, the sense of motion is, by all appearances, seamless.
What is a Solar Prominence?
A solar prominence (also known as a filament when viewed against the solar disk) is a large, bright feature extending outward from the Sun's surface. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's hot outer atmosphere, called the corona. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. Scientists are still researching how and why prominences are formed.
The red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma.
“It is not uncommon for prominence material to drain back to the surface as well as escape during an eruption,” states Holly Gilbert a Goddard solar physicist. “In fact, it’s a little strange when ALL of the mass escapes. Prominences are large structures, so once the magnetic fields supporting the mass are stretched out so that they are more vertical, it allows an easy path for some of the mass to drain back down.”
When a prominence erupts, the released material is part of a larger magnetic structure called Coronal Mass Ejections (CMEs). When directed toward Earth, CMEs can interact with our Earth’s magnetic field and trigger a geomagnetic storm, with bright auroras and the potential for disturbance in communications and electrical power networks.
Scientists at NASA study such “space weather” events intensely in hopes of predicting them better someday.