The first "Mars quake" has been detected, NASA announced Tuesday.
The finding "officially kicks off a new field: Martian seismology!," said Bruce Banerdt of NASA’s Jet Propulsion Laboratory.
NASA said this is the first trembling that appears to have come from inside the planet, as opposed to being caused by forces above the surface, such as wind.
The sound was detected by NASA's Insight Lander, a robot spacecraft that's now sitting on the Martian surface. The sound was detected on April 6, 2019.
Three distinct kinds of sounds can be heard, all of them detected as ground vibrations by the spacecraft's seismometer: noise from Martian wind, the quake itself, and the spacecraft's robotic arm as it moves to take pictures.