For the first time, spacecraft catch a solar shockwave in the act
On Oct. 8, 2013, an explosion on the sun’s surface sent a supersonic blast wave of solar wind out into space. This shockwave tore past Mercury and Venus, blitzing by the moon before streaming toward Earth. The shockwave struck a massive blow to the Earth’s magnetic field, setting off a magnetized sound pulse around the planet. NASA’s Van Allen Probes, twin spacecraft orbiting within the radiation belts deep inside the Earth’s magnetic field, captured the effects of the solar shockwave just before and after it struck. Now scientists at MIT’s Haystack Observatory, the University of Colorado, and elsewhere have analyzed the probes’ data, and observed a sudden and dramatic effect in the shockwave’s aftermath: The resulting magnetosonic pulse, lasting just 60 seconds, reverberated through the Earth’s radiation belts, accelerating certain particles to ultrahigh energies. “These are very lightweight particles, but they are ultrarelativistic, killer electrons — electrons that can go right through a...