The Sun may appear to be a stable and monolithic body sitting at the heart of the Solar System, but that isn’t the case. Our star is rocking with ‘starquakes’ that have become an area of intense study for solar physicists. Beneath the Sun’s surface is a roiling and violent sea of plasma that transfers energy from its core, where it’s generated by the nuclear fusion of hydrogen to helium, to the Sun’s surface, the photosphere, where it can be radiated out to rain sunlight down on Earth and the other planets. This process causes our star to shake, a phenomenon generally referred to as a starquake. Though only the surface of the Sun is visible to us, humanity has learned to deduce what lies beneath using these starquakes, just as seismic waves from earthquakes have been used to decode the interior of our planet. Now, this practice is being used to understand the interiors of more distant stars of all shapes, sizes and ages.
Though the name starquakes is reminiscent of earthquakes because stars are essentially superheated balls of gas, the causes of the two phenomena are very different. “I know it’s a good way of catching people’s attention to call them starquakes, and there are some analogies with earthquakes, but we generally talk about starquakes as the oscillations of stars,” University of Toulouse scientist Sébastien Deheuvels. “An earthquake is something that very locally pushes the Earth to oscillate, but what we see for a star is the whole star oscillating, not just a part of it. So perhaps the most common analogy that we make is with musical instruments – when you pluck a guitar string, the whole string of the guitar oscillates.”
