The InSight lander was sent to Mars to study the planet's interior, mostly by way of marsquakes. As you may have guessed, these are seismic tremors similar to earthquakes on our home planet, but because Mars doesn't have plate tectonics they're generally much weaker. Nevertheless, they can provide some clear insights into the structure and composition of the different layers below the red surface. Contact with the probe was lost in December 2022, but there's still much to be gleaned from the data it gathered during its tenure. In the new study, NASA scientists have made direct observations of the Red Planet's core, thanks to a pair of quakes that occurred on August 25 and September 18, 2021. These were the first events detected from the opposite side of the planet, meaning their seismic waves had to travel farther to reach the detector, passing through the core on the way.