Almost 44 years ago, in September 1977, NASAsent on a journey the space probe Voyager 1, which today, having completed the main task of studying Jupiter and Saturn, continues to supply scientific information, being already outside the solar system.
New scientific evidence coming from the ancientspacecraft (by the standards of the Earth's space age), allowed astronomers to study interstellar space and make sure that there is not only a vacuum outside the solar system. According to the information transmitted by Voyager 1, we can conclude that interstellar space is filled with plasma - interstellar gas that produces acoustic noise recorded by the Earth probe.
Today, Voyager 1 is transmitting data fromdistances over 22.5 billion km from the Sun. Astronomers from Cornell University recorded in a narrow frequency "a faint and monotonous, constant hum of interstellar gas." It is noteworthy that the device operates outside the heliosphere (the boundaries of the solar system with interstellar space), and the Sun with the planets of "our" system has practically no effect on the indicators recorded by the probe.
Voyager 1 uses the Plasma Wave System, which was used to study the magnetospheres of Jupiter and Saturn, to obtain data on interstellar noise.
The journey beyond the heliosphere continuessince August 2012. Since then, the space probe has recorded a constant, monotonous hum, which astronomers have compared to the "quiet noise of rain." At the same time, Voyager 1 recorded in 2014 a burst of activity from the Sun, which then ejected coronal matter, which caused a change in the magnetic field even outside the heliosphere. Scientists compare such bursts with lightning during the rain, after which there is a calm and interstellar space continues to emit a "quiet rustle of rain."