Since 2012, NASA’s Voyager 1 spacecraft has experienced three ‘tsunami waves’ in interstellar space. The most recent, which reached the spacecraft earlier this year, is still propagating outward according to new data. It is the longest-lasting shock wave that researchers have seen in interstellar space.
A “tsunami wave” occurs when the sun emits a coronal mass ejection, throwing out a magnetic cloud of plasma from its surface. This generates a wave of pressure. When the wave runs into the interstellar plasma — the charged particles found in the space between the stars — a shock wave results that perturbs the plasma.