The European Space Agency has released this audio of the "song" coming from comet 67P/Churyumov-Gerasimenko. The recording was made by the Rosetta spacecraft as it approached the comet.

The ESA says the sound seems to come from oscillations in the magnetic field around the comet, but exactly how the noise is being produced remains a mystery.

The "song" has a frequency of 40-50 millihertz, which is far below the normal human hearing range of 20 Hz to 20 kHz.

The ESA said the frequency had to be raised by a factor of about 100,000 to make it audible to humans.