What exploded on the sun last Thursday morning?
The eruption that occurred on the sun last week, February 24, was many times larger than Earth in scale and represented a tremendous release of energy. But what exactly happened? Here is a wide view of the event:
This type of event is called a prominence eruption. It occurs in the extended, hot outer atmosphere of the sun, called the corona. The material that appears to glow red is plasma, a mix of electrically charged hydrogen and helium.
OK, now let’s take a closer look. Here is a close-up view of the prominence:
The plasma is flowing along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. Prominences occur when such a structure becomes unstable and bursts outward, releasing plasma.
At Goddard, Holly Gilbert is one of the physicists trying to understand what triggers such explosive events. We have a pretty good idea of what prominence eruptions are, but less of a clear idea of what causes them.
“Here you have a magnetic structure that holds prominence plasma and somehow become unstable and erupts,” Gilbert says, “and by doing so you get this beautiful structure not only flying outward and escaping the gravitational field, but only also draining back because the magnetic topology allows it to do so. What we’re not sure of is what is initiating the eruption.”
In the video, the event appears to stop and start playing backward. But this is not so. Actually, plasma is falling back toward the sun and flowing along the complex surfaces formed by magnetism around the sun.
“It is not uncommon for prominence material to drain back to the surface as well as escape during an eruption,” Gilbert says. “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.”
This particular eruption was not directed toward Earth. If it were, the material released and its imprinted magnetic field might have triggered 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.
OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.