As our sun erupts with flares and coronal mass ejections (CMEs), powerful shock waves propagate throughout the heliosphere and past the planets. Eventually, the effects of these violent eruptions catch up to, and overtake, the Voyager 1 probe. In the case of this most recent event, the sun erupted about a year ago and only now is the shock wave being detected.
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The solar "tsunami" has traveled through the heliopause (the outermost boundary of the heliosphere) and washed through the interstellar plasma, causing the electrons in the plasma to "ring." The shock wave also has an impact on high-energy cosmic rays that Voyager can also detect.
"The tsunami wave rings the plasma like a bell," said Stone. "While the plasma wave instrument (on board Voyager 1) lets us measure the frequency of this ringing, the cosmic ray instrument reveals what struck the bell - the shock wave from the sun."
Since Voyager 1 entered interstellar space in 2012, this is the third such wave it recorded. Each event has helped mission scientists characterize the interstellar environment, a region where no man-made spacecraft has ever traveled through before.