New 'Tsunami Wave' from Sun Hits Voyager 1

Voyager 1 was hit by a new 'tsunami' shock wave from the Sun, NASA said.

These waves, hitting the craft in 2013, had led researchers to believe that Voyager had left our sun's bubble and was entering the interstellar space.

"Normally, interstellar space is like a quiet lake," said Ed Stone of the California Institute of Technology in Pasadena, California, the mission's project scientist since 1972. "But when our sun has a burst, it sends a shock wave outward that reaches Voyager about a year later. The wave causes the plasma surrounding the spacecraft to sing."

Voyager 1 and Voyager 2 were launched 16 days apart in 1977. These crafts are the first man-made objects to explore interstellar region.

According to NASA, the newest wave to hit Voyager confirms that the probe is in the interstellar space. The mission, however, hasn't left the solar system because it is yet to reach a final halo of comets surrounding our sun.

Interstellar space is the region between the stars and is filled with thin soup of charged particles called plasma.

"All is not quiet around Voyager," said Don Gurnett of the University of Iowa, Iowa City, the principal investigator of the plasma wave instrument on Voyager, which collected the definitive evidence that Voyager 1 had left the sun's heliosphere, according to NASA. "We're excited to analyze these new data. So far, we can say that it confirms we are in interstellar space."

So, how do scientists know that the probe was hit by a shock wave from the Sun? NASA said that the sun's shock waves push electrically-charged particles like buoys in a tsunami. Cosmic ray instrument on the craft tells the researchers that a shock wave from the sun has hit the probe.

Another instrument on Voyager called plasma wave instrument can detect oscillations of the plasma electrons, NASA said.

"The tsunami wave rings the plasma like a bell," said Stone. "While the plasma wave instrument lets us measure the frequency of this ringing, the cosmic ray instrument reveals what struck the bell -- the shock wave from the sun."

Voyager 1 has been hit by three such cosmic waves since it entered the interstellar space in 2012. The first was too weak to be detected at the time of the event. The second was clearly registered in March 2013.