In March of 2015, the sun exploded. Not all the way, of course, but a massive solar flare sent a shockwave rippling toward Earth that created the most jarring disturbance of the planet’s magnetic field in the last decade.
The solar flare, technically called a “coronal mass ejection,” and resulting geomagnetic storm threw off the Earth’s Van Allen radiation belts — a region of Earth’s outer atmosphere ensconced between layers of the magnetic field and home to a particularly nasty blanket of radiation. Fortunately, NASA’s Van Allen Probes caught the whole thing on their instruments, and recorded the unprecedented findings, which are now published in the Journal of Geophysical Research
The tight relationship between the magnetosphere and Van Allen belts means a geomagnetic storm could seriously impact life for humans down here by damaging critical technology like communications instruments and power grids. The only way to tell what the damage might be, however, is to get a close look.
Luckily, on that fateful spring day last year, one of NASA’s Van Allen probes just happened to be orbiting right through the belts and captured the very rare phenomenon in high-resolution.
The spacecraft measured pulses of electrons that were energized to speeds nearly as fast as light. Although the shockwave from the coronal mass ejection soon dissipated, it left behind a very dynamic radiation environment that persisted for many days afterward. Understanding exactly how this radiation behaves in the aftermath is key to knowing more about how our planet interacts with the sun, as well as how humans can protect vital equipment in orbit and on the surface from being fried by space weather.
Photos via NASA's Goddard Space Flight Center; Tom Bridgman, animator