On March 29th, the sun released an X-class flare. It was caught by five high-quality solar observatories on the ground and in space, creating the most detailed observations of an intense flare in history. This beautiful, rich data will help researchers better understand what triggers flares.
Composite of data sources capturing the flare: SDO [bottom/left], IRIS [darker orange square], Dunn Solar Telescope [red rectangle], RHESSI [violet spots]. Credit: NASA
X-class flares are the biggest of the big, the highest-energy and brightest of solar flares. The March 29th event was an X1 flare, the lowest intensity within the X-class category.
Composite of many (but not all) of the data sources capturing the flare.
The flare was observed by NASA's Interface Region Imaging Spectrograph (IRIS), Solar Dynamics Observatory (SDO) and Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI); the Japanese Aerospace Exploration Agency's Hinode; and the National Solar Observatory's ground-based Dunn Solar Telescope.
Flare ribbon in the overlain on a footprint of the sunspot underlaying the flare.
Credit: Lucia Kleint (BAER Institute)/Paul Higgins (Trinity College Dublin, Ireland)
It might seem like a ground-based telescope has little to add to the quartet of space telescopes, but it's the linchpin that co-ordinates the action. The Dunn Solar Telescope was on a ten-day mission to hunt for flares, and had identified an active region with intense magnetic fields in close proximity. Hoping this was the harbinger of a solar eruption, the team requested three of the space telescopes add the region to their observation schedule. They did, reorienting just in time to capture the event.
RHESSI didn't produce beautiful images, but did capture the intense flare-accelerated electrons in the footprint of the flare [left] and the roasting hot 25 million Kelvin temperature in the corona flare loop [right]. Credit: NASA/RHESSI
Besides the five observatories focusing on the primary flare, several other telescopes captured secondary events. NASA's Solar Terrestrial Relations Observatory (STEREO) and the ESA/NASA Solar and Heliospheric Observatory (SOHO) observed the related coronal mass ejection, while the National Oceanic and Atmospheric Administration's Geostationary Operational Environmental Satellite (GOES) measured the flare's X-rays, and other spacecraft watched the effects of the flare as it propagated through space.
Overall, this means the solar flare was watched by more observatories with more coordination than any other flare in history. The detailed data from so many sources and so many instruments will hopefully lead to a better understanding of what causes these solar explosions, and maybe even a better ability to predict when they'll happen.
Each image of the flare is progressively higher in the sun's atmosphere, from the chromosphere [upper left] to 3,000 miles above the surface [lower right]. Credit: JAXA/NASA/Hinode/EIS
This was the first X-class flare observed by the IRIS spacecraft, which only launched in June 2013. The purpose of the craft is to observe the interface region between the chromosphere and transition layers, and this was the first-ever observations of what happens in it during the formation of an intense flare.
The first X-class flare imaged by IRSI. Credit: NASA/IRIS
While this flare posed no threat to Earth, that's an element of pure luck. Massive flares can knock out the power grid, where on a large enough scale that's a downright catastrophic threat to civilization.
Why do we care? NASA puts it eloquently:
To have a record of such an intense flare from so many observatories is unprecedented. Such research can help scientists better understand what catalyst sets off these large explosions on the sun. Perhaps we may even some day be able to predict their onset and forewarn of the radio blackouts solar flares can cause near Earth - blackouts that can interfere with airplane, ship and military communications.
Not every observation produces beautiful images. The GOES satellite recorded a spike in X-rays from the sun, the signature of a solar flare. Credit: GOES
NASA will be hosting a Hangout about the flare on April 8. You might also like this rather unusual-looking cavitation event.