On May 12, the Voyager 1 spacecraft, which was launched by the US Space Agency from Florida (USA) nearly 44 years ago, detected a humming sound coming from outside the solar system.
According to research published in the journal Nature Astronomy, instruments aboard Voyager 1 detect plasma wave sounds after the spacecraft has passed the edge of the solar system.
The team led by Cornell University (USA) made the unexpected discovery while studying data transmitted by this spacecraft from a distance of 22.5 billion km.
They said the audible sound was weak and even because it was a narrow band, and suggested that the humming came from interstellar gas.
However, from about late 2012 to 2013, when it began to enter interstellar space, Voyager 1 recorded strange sounds with the instrument’s plasma wave system on board.
The scientists found that the sound gradually increased in pitch each time it appeared. Accordingly, the horizontal dashed line shows that the sound will increase along the same slope. This means that the density of interstellar gas in the region Voyager 1 passes through is gradually increasing.
The Voyager 1 spacecraft was first launched on September 9, 1977, then passed Jupiter in 1979 and Saturn in 1980, before crossing the edge of the solar system in August 2012.
To date, the Voyager 1 spacecraft is the farthest human device into space and continues to operate, sending data back even at great distances and decades on. Data from the spacecraft’s exploratory flights can help scientists understand more about the interaction between the interstellar medium and the solar wind.