#BBCtrending: Rosetta comet sings loud and clear

The sound coming from comet 67P/Churyumov-Gerasimenko has caught the imagination of hundreds of thousands on social media.

"Maybe it's the sound of an alien shouting 'help me, I'm trapped inside a comet'," Alan Hayward commented on SoundCloud, the audio sharing network. This was where the European Space Agency posted the audio of the sound being captured by their Rosetta spacecraft, from which the probe to land on the comet is being deployed. "Is that you, Predator?" asked another user, Reactor Four. Another, Ronnie Wonders said: "This is wonderful. It would be arrogant to think we are alone in this universe. Not saying it's aliens but I'm really looking forward to finding out what is making this sound."

For their part, the scientists are just as surprised as social media users. "This is exciting because it is completely new to us. We did not expect this and we are still working to understand the physics of what is happening," Karl-Heinz Glaßmeier, head of Space Physics and Space Sensorics at the Technische Universität Braunschweig, Germany, explained on the RESA Rosetta blog. The "song" - as the scientists themselves refer to it- was in fact outside the normal range of human hearing range and has to be boosted in volume by a factor of 10,000. According to scientific theory, the comet releases neutral particles into space where they collide with high-energy particles and that's what makes the sound. However, "the precise physical mechanism behind the oscillations remains a mystery," according to the blog.

"It reminds me of the music of [computer game] Manic Miner," another user, Bleakside, posted after listening to the 1:27-minute-long audio clip. "Some ET making popcorn on that planet," Dan Maxe commented. The audio clip has been played over 336,000 times on SoundCloud and been shared 13,000 times on Facebook

Audio courtesy of ESA/Rosetta/RPC/RPC-Mag

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