NASA's Voyager 1 spacecraft is continuously experiencing a "Tsunami wave" as it enter the interstellar medium beyond the solar system.The spacecraft launched in 1977 is the farthest [travelling 19.5 billion km(approx) away from earth] man made object has gone from Earth ever.
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.
This is the third shock wave that Voyager 1 has experienced. The first was in October to November of 2012, and the second was in April to May of 2013.Researchers are uncertain as how fast the wave is moving or how broad region it covers.
The second tsunami wave helped researchers to determine that Voyager 1 had left the heliosphere [the bubble created by the solar wind encompassing the sun] and the planets in our solar system.
One thing for sure that Voyager has entered a frontier where no spacecraft had gone before,The Interstellar Space.
Signals from Voyager 1 takes 36 hours and 14 minutes [approx] to reach Earth.