Scientists have discovered that Mars has a solid inner core, similar to Earth’s, surrounded by a molten outer core.

Using seismic data from NASA’s InSight lander, the team found the inner core extends about 380 miles (613 km) from the planet’s center and is likely made of iron, nickel, and lighter elements like oxygen.

The outer core stretches up to 1,100 miles (1,800 km), the Associated Press has reported.

The findings shed light on Mars’ interior structure and magnetic history, though further study is limited now that InSight has stopped transmitting.