Two NASA spacecraft have provided the most comprehensive movie ever of a mysterious process at the heart
of all explosions on the sun: magnetic reconnection.
Magnetic reconnection happens when magnetic field lines come together, break apart and then exchange partners,
snapping into new positions and releasing a jolt of magnetic energy.
This process lies at the heart of giant explosions on the sun, such as solar flares and coronal mass ejections,
which can fling radiation and particles across the solar system.
Take a look at NASA's video below - to better understand the process:
NASA - Magnetic Reconnection
SDO Sees Reconnection
Scientists want to better understand this process so they can provide advance warning of such space weather,
which can affect satellites near Earth and interfere with radio communications.
Click on image to enlarge
An overlap of data from two NASA spacecraft confirm a sighting of magnetic reconnection on the sun, a process of realigning magnetic fields that lies at the heart of space weather. The teal image, from SDO, shows the shape of magnetic field lines in the sunís atmosphere. The RHESSI data, in orange,
Image Credit: NASA/SDO/RHESSI/Goddard
One reason why it's so hard to study is that magnetic reconnection can't be witnessed directly, because magnetic
fields are invisible.
Instead, scientists use a combination of computer modeling and a scant sampling of observations around magnetic
reconnection events to attempt to understand what's going on.
"The community is still trying to understand how magnetic reconnection causes flares," said Yang Su, a solar
scientist at the University of Graz in Austria.
"We have so many pieces of evidence, but the picture is not yet complete."
When searching through observations from NASA's SDO, short for Solar Dynamics Observatory, Su saw direct
images of magnetic reconnection as it was happening on the sun.
The process of magnetic reconnection has already been imaged by scientists.
However, now, for the first time,
scientists could show a very comprehensive set of data that can be used to constrain and improve models
of this fundamental process on the sun.
When magnetic fields lines on the sun come together they can realign into a new configuration. The process, called magnetic reconnection, can produce tremendous amounts of energy, powering gigantic explosions in the sunís atmosphere.
Image Credit: NASA Goddard
Magnetic field lines, themselves, are indeed invisible, but they naturally force charged particles - the
material, called plasma, which makes up the sun - to course along their length. Space telescopes can see
that material appearing as bright lines looping and arcing through the sun's atmosphere, and so map out
the presence of magnetic field lines.
Looking at a series of images, Su saw two bundles of field lines move toward each other, meet briefly to form
what appeared to be an "X" and then shoot apart with one set of lines and its attendant particles leaping into
space and one set falling back down onto the sun.
"It can often be hard to tell what's truly happening in three dimensions from these images, since the pictures
themselves are two-dimensional," said Gordon Holman, a solar scientist at
NASA's Goddard Space Flight Center in Greenbelt, Md., who is also an author on the paper.
"But if you look long enough and compare data from other instruments, you can make a good case for what's going on."
"This is the first time we've seen the entire, detailed structure of this process, because of the high quality data from SDO," Su said.
"It supports the whole picture of reconnection, with visual evidence."
The results are published in Nature Physics on July 14, 2013.
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