http://news.discovery.com/space/comet-sings-mysterious-song-to-rosetta-141111.htm
As if to celebrate tomorrow’s landing of Philae on the surface of Comet 67P/Churyumov-Gerasimenko, the European Rosetta mission has detected a mysterious signal coming from the 2.5 mile-wide lump of ice and rock.
But when recording signals in the 40-50 millihertz frequency range, the RPC stumbled on a surprise — the comet was singing.
Through some kind of interaction in the comet’s environment, 67P’s weak magnetic field seems to be oscillating at low frequencies. In an effort to better understand this unique ‘song’, mission scientists have increased the frequency 10,000 times to make it audible to the human ear. This is the result.