Vibrating particles
Consider how sound actually works: a vibrating object causes nearby particles (molecules and atoms) in the surrounding medium (solid matter, air, or other gas) to vibrate also, transferring energy from one particle to the next. The more densely packed the particles, the better sounds is transmitted. So objects in space such as stars and planets can certainly create sounds -but the space in between these objects is a near-vacuum. The very few particles that do exist out there are far too widely separated to be able to transmit sounds at a level that our ears can pick up. So it's true, space IS silent, in that we cannot directly hear any sounds outside our world.
Despite this, sound waves are now playing an increasing important part in astronomy in various fields. The key point is that their vibrations involve transfers of energy, a concept that is central to astronomy, and the effects of this energy transfer can be observed in other ways too.
Hot Jupiter
Take Jupiter for example. Astronomers have long been puzzled by the high temperatures at the outer surface of the atmosphere of the massive planet - it is much hotter than can be accounted for by solar warming. Last week, new research suggested a rather off-beat cause – sound waves! To be more precise, they suggest that the unexplained heat may be caused by acoustic waves from turbulent thunderstorms within the Great Red Spot. Yes, sound waves can actually generate significant heat!
Another branch of astronomy based on acoustics is astero-seismology. Many stars, including our Sun, are boiling masses of gas, and the acoustic vibrations set up by the movements of the gas make the star resonate and 'ring like a bell', giving rise to distinctive patterns of oscillations on the surface.
Telescopes can observe these oscillations as specific patterns of brightenings and dimmings, and amazingly, these patterns can then be interpreted to find out more about the composition of the interior of the star.
This recently developed technique is delivering impressively detailed results - it's a method of actually looking inside distant stars that appear to us as just a point of light. Incredible!
| Astronomy in audio form Not only can astronomers observe the visible effects of acoustic action, it's also possible to convert non-acoustic phenomena into sound form so that we can listen to them. A familiar example is radio transmissions – in fact the sound that we hear from our radio is the result of mechanically converting very long-wave electromagnetic signals (a form of light) into sound waves that we can hear,via a speaker. Developing this technique, astronomers have started 'sonifying' other astronomical signals in order to analyse them. It's a powerful technique because it seems the human ear is extremely good at picking out oddities. |
The universe it seems is full of sound, and the 'music of the spheres', while perhaps not quite how ancient astronomers imagined, is very real indeed!
1. NASA's Goddard Space Flight Center
2. ESO
3. Robert Alexander, NASA/University of Michigan