A new movie from the Japanese Hinode spacecraft is one of the most detailed glimpses of a solar flare ever made and has helped scientists see what's behind the colossal eruption.
Sunspots are cooler regions of the sun's surface where magnetic energy caps the superheated material below. Sometimes the cap unleashes a flare, similar to soda exploding from a shaken can.
Hinode can spot solar details as small as 90 miles wide, even though it's 93 million miles from the sun.
Other data gathered by the spacecraft gave astronomers an unprecedented view of the magnetic underpinnings of the flare.
"Solar flares are essentially magnetic," said John Davis, NASA's project scientist for Hinode at the Marshall Space Flight Center.
In the maelstrom above a sunspot, lines of magnetic force are twisted and stretched until the tension reaches a certain point — and then the whole thing explodes. A rubber band provides a good analogy, Davis suggested in a NASA statement. Hold one end in each hand, stretch it and twist until the band snaps.
Magnetic fields behave a lot like rubber bands, and "Hinode was able to see the twisting and stretching that preceded the Dec. 13th solar flare," Davis said.
The Dec. 13 flare was an X-3. All X-flares are major, with higher numbers indicated greater releases of energy. This one created a coronal mass ejection, or giant expanding bubble of charged particles. The CME interacted with Earth's magnetic field to produce Northern Lights as far south as Arizona.
Hinode is poised to help researchers unravel remaining mysteries about how solar flares and storms work, but the sun is in a low period of activity in its 11-year cycle.
"The kind of data we're getting from Hinode is just what we need to sort out how flares work," Davis said. "All we need now is some more explosions."
Some forecasters expect the next peak in the solar cycle, due to begin ramping up in a couple years, to be one of the strongest on record. Enhanced activity means satellites and even power grids on Earth are at risk of electrical malfunction. Hinode is joined by NASA's new 3-D STEREO spacecraft to provide better forecasting ability than during past cycles.