Mars' core looks bigger than it is because it's wrapped in radioactive magma

Oct 26: Data from a meteorite impact on Mars that was recorded by NASA’s InSight lander in 2021 is now helping to clear up some confusion about the red planet’s interior makeup. A pair of studies published today in the journal Nature separately determined that Mars’ iron-rich core is smaller and denser than previous measurements suggested, and it’s surrounded by molten rock.

The now-defunct InSight lander, which arrived on Mars in November 2018, spent four years recording seismic waves produced by marsquakes so scientists could get a better understanding of what’s going on beneath the planet’s surface. But, estimates of the Martian core based on InSight’s initial readings from nearby quakes didn’t quite add up. At the time, scientists found the core’s radius to be somewhere between 1118 and 1149 miles — much larger than expected — and that it contained a perplexingly high amount of lighter elements complementing its heavy liquid iron.