As part of the Melbourne Festival, percussion group Speak Percussion will perform Gerard Grisley’s Le Noir de l’Etoile (the Black of the Star), tonight and tomorrow night, in Melbourne’s Federation Square.

Described as an “electro-acoustic masterwork”, the piece was inspired by the thrumming sounds made by spinning pulsars. What makes this particular show unique compared to previous performances is that this time around, the group are now using new pulsar recordings based on data collected radio telescopes such as our Parkes radio telescope.

But what does a pulsar sound like?

Pulsars are rotating neutron stars, characterised by beams of radiation streaming from their magnetic poles. As the pulsar spins these radiation beams may be detected by Earth-based radio telescopes, much in the same way you see the beam of beam of light from a lighthouse.

A spinning pulsar – characterised by its magnetic field and the streams of radiation beamed along the magnetic poles. Source: Michael Kramer (University of Manchester).

As the beam swings past, the observer will note a regular pulse in the data as the radiation is detected. If these data blips are recorded and played through a speaker, the sound of that particular pulsar can be ‘heard’ in the form of a beat.

Different pulsars spin at different speeds, and no two pulsars will sound the same. Some may result in regular pulses, like a patient drummer beating on a drum; other pulsars are faster and sound like helicopter blades; while others spin so fast that the resulting sound blends together into a long hum.

If you were to overlay multiple recordings of pulsars, the result can be a fascinating mix of beats and tones that captivates the listener.

But it’s much more than aural enjoyment, there is a scientific benefit of ‘listening’ to pulsars as well. According to astronomer George Hobbs, listening to the sounds of pulsars can help researchers analyse data and discover features that may not have been picked up by just looking at the data stream on a computer screen.

Moreover, it can also be a great tool to use in Outreach activities such as our PULSE@Parkes program, where students can control the Parkes telescope, determine the properties of various pulsars, and feed into a growing database used by professional astronomers.

“Sometimes it’s easy to miss the fundamental part of this research, which is that we get data streams from space and add them together to see the output,” says George. “Not only is it a good way to help us visualise the pulses, it’s also a cool real-life thing for students to do with the Parkes telescope.”

The following video provides a lovely introduction from a different performance of the Black of the Star:

For more information on Speak Percussion, listen to the story which aired on ABC radio earlier this week about this week’s performances.