In space, no one can hear...

...well, maybe. Chinese astronaut Yang Liwei heard a "knocking" sound while alone in orbit - and a similar sound has also been reported by subsequent missions.

He's not alone. NASA astronauts heard this sound when on the far side of the moon, explained as some kind of radio interference. And this video is the song of Jupiter, which produces a lot of radio interference. The bit at the end sounds rather like the TARDIS.

The knocking, however, has not been explained, with the most likely theory being micro meteorite strikes - and something about the Chinese ship causing it to "ring" like a bell when struck.

Space, not quite as silent as we thought. (Although still no whoosh from passing ships ;)).