Saturn has a strange electromagnetic relationship with Enceladus, and scientists have captured snippets of this bond in a short audio clip that observers on Earth can listen to.
Just before NASA's Cassini spacecraft plummeted to its end in Saturn's swirling gases in mid-September last year, the interplanetary probe caught wind of a peculiar interaction between the magnetic fields of Saturn and Enceladus.
Cassini found that waves of highly charged particles called plasma are traveling between the gas giant and its sixth largest moon.
Enceladus Interacts With Saturn
Among Saturn's 62 satellites, Enceladus is one of the most remarkable. Experts believe this icy little world brings a lot of promise to the search for alien life. Underneath the moon's harsh surface is a warm ocean spewing geyser-like jets of hot vapor and complex organic molecules into the atmosphere.
These clouds of hot vapor emitted from beneath the surface of Enceladus reach Saturn's ionosphere and mess with the ringed planet's electrical energies. Enceladus also has its own magnetic field, which brings more chaos to the fore.
However, it is not just Enceladus making a move. Saturn responds by sending a column of oscillating plasma through its magnetic field lines, which act as electrical circuits, to reach its rings and Enceladus.
Saturn Sings To Enceladus
In a new paper published in the Geophysical Research Letters, astronomers have demonstrated for the first time what the waves that go back and forth between Saturn and Enceladus sound like.
These waves are actually plasma vibrations that resemble the vibrations of sound that travel through air. Using data gathered by the Radio Plasma Wave Science (RPWS) instrument onboard Cassini during the final days of the probe's Grand Finale mission, the scientists were able to observe the vibrations and convert it into a sound audible on Earth.
The data, recorded on Sept. 2, 2017, is the first time researchers have heard the vibrating pulses of plasma being sent back and forth between Saturn and Enceladus.
"Enceladus is this little generator going around Saturn, and we know it is a continuous source of energy," says lead author Ali Sulaiman of the University of Iowa and the RPWS team. "Now we find that Saturn responds by launching signals in the form of plasma waves, through the circuit of magnetic field lines connecting it to Enceladus hundreds of thousands of miles away."
Scientists Convert Plasma Waves Into Sound
The sound is what scientists call an auroral hiss. The name comes from the plasma, a soup of electrically charged particles that make up the spectacular auroras lighting up the Earth's north and south poles. In the same way as water and air create waves to carry energy, so too does plasma.
It is important to note that no actual sound can be heard if one passes between Saturn and Enceladus. Sound is a wave that is carried by a medium, such as air. It is only perceived as sound once it hits the eardrum. Because there is no air in space, the waves being sent by Saturn to Enceladus cannot be heard.
However, electromagnetic signals can freely travel in space. This means they can be converted into sound using the same man-made radio technology used to convert signals from radio towers to a car stereo. Plasma waves are also electromagnetic in nature, which is what allowed scientists to convert them into sound that can be played and amplified through speakers.
The scientists converted the 16-minute recording into 28.5 seconds of a strange whooshing, hissing, and clicking cosmic sound.