Comet song

Once orbiting Comet 67P, the Rosetta spacecraft began to collect data on the plasma field of the comet. The data revealed a very unexpected event – a comet song. Avionics engineer Warwick Holmes explains this unexpected finding that has excited plasma scientists.

Point of interest
Space is a vacuum with no sound. In order to ‘hear’ the comet song, scientists converted the electrical signals (the wavelengths) from the comet into sound.

Transcript

WARWICK HOLMES

So we’ve been in orbit, and we then started measuring what we call the plasma field. The plasma field is where the evaporated material coming of the comet gets ionised by the Sun, and it gets modulated by the solar wind

There’s a gas coming off the comet, which is then activated by the Sun, and it wobbles. That’s interesting, we could see the wobble on the electric measurements. We thought, why don’t we speed those up and put them through a speaker and try and listen to what the comet is singing? So this is what a comet sounds like from half a billion kilometres outside the asteroid belt.

Now that is the sound of a comet, believe it or not. Obviously, we can’t hear it, it’s in a hard vacuum, but electrically, it’s creating a signal which we can amplify and measure and convert into a sound. And you hear the frequencies going up and down. There’s all sorts of weird things going on, we don’t know what they are. We’ve got no idea what’s creating this, but the plasma consortium scientists have gone berserk now trying to figure out what on earth is this?  Because it’s a very, very interesting signal. The comet is extremely cold, it’s extremely far from the Sun, yet it’s in fact very active. And this is an unexpected, a very much unexpected event.

The Science Learning Hub would like to acknowledge the following for their contribution to this resource:
Warwick Holmes
Lecture video footage courtesy of the University of Waikato
Still of Comet 67P courtesy of ESA/Rosetta/NavCam and released under Creative Commons licence 3.0