Scientists at NASA have reported an exciting detection by its Insight lander on Mars - mysterious rumblings coming from the interior of the planet. The researchers believe the seismic events may be caused by a sudden release of energy from the planet's interior, but the nature of that release remains unknown and puzzling. Intriguingly, the new rumblings are believed to have originated in a location on Mars called Cerberus Fossae, where two other previous candidate events are believed to have originated. Although these rumblings have sometimes been called "Marsquakes" the planet is not believed to have a similarly active tectonic system like Earth's that causes earthquakes. And curiously, the previous seismic events detected by the space agency's InSight lander - which arrived on the planet's surface in 2018 - occurred almost a full Martian year ago, or two Earth years, during the Martian northern summer.

InSight's primary instrument is a French-built seismometer, designed to detect the slightest vibrations from "marsquakes" around the planet. The device, to be placed on the surface by the lander's robot arm, is so sensitive it can measure a seismic wave just one-half the radius of a hydrogen atom.