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A "strong to severe" geomagnetic storm hit Earth yesterday, NASA says, after the sun unleashed a burst of plasma from a turbulent region two days prior.
The region, known as sunspot 1302, has sent forth a few blasts of energy called solar flares, including a flare and an accompanying belch of plasma called a coronal mass ejection (CME) on September 24. The CME reached Earth two days later and impacted the planet's magnetic shielding, exposing high-altitude satellites to charged particles and magnetic fields, according to NASA. The CME's arrival also produced low-latitude auroras—spaceweather.com reports that sightings of the not-so-northern lights were reported in Michigan, New York, South Dakota, Maine and Minnesota.
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According to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center, high-accuracy GPS services were affected by the storm.
An earlier flare from sunspot 1302 was more powerful but did not aim a blow at Earth—the X1.9-category flare captured on the video below by NASA's Solar Dynamics Observatory erupted about three hours before the M-class, or medium-size, flare accompanying the CME. X is the most powerful class of flare, and the numerical suffix indicates the relative brightness of the flare within that class. (An X9 is the brightest classification on the scale.)
Video credit: NASA/SDO/GOES