Rosetta records mysterious 'singing sound' from its target comet

Rosetta's Plasma Consortium (RPC) has recently recorded a mysterious 'singing sound' from its target comet 67P/Churyumov-Gerasimenko into space.

The comet seems to be emitting a 'song' in the form of oscillations in the magnetic field in the comet's environment. It is being sung at 40-50 millihertz, far below human hearing, which typically picks up sound between 20 Hz and 20 kHz. To make the music audible to the human ear, the frequencies have been increased by a factor of about 10,000.

The music was heard clearly by the magnetometer experiment (RPC-Mag) for the first time in August, when Rosetta drew to within 100 km of 67P/C-G.

The scientists think it must be produced in some way by the activity of the comet, as it releases neutral particles into space where they become electrically charged due to a process called ionisation. But the precise physical mechanism behind the oscillations remains a mystery.