On Wednesday, September 3, 2025, scientists reported that Mars has a solid inner core made mostly of metal. This result came from data collected by NASA’s InSight lander, which recorded more than 1,300 marsquakes before it stopped working in 2022. The spacecraft landed near the equator of Mars in 2018. Past studies suggested the center of Mars was liquid, but the new research shows a solid core with liquid metal around it. The journal Nature said the solid core reaches about 380 miles (613 kilometers) from the planet’s center. It is likely made of iron and nickel, with some lighter elements such as oxygen. The outer core is larger, reaching up to 1,100 miles (1,800 kilometers). Scientists also explained that the solid core may still be slowly crystallizing today.

The study used 23 marsquakes for its results. Evidence showed the inner core is about one-fifth of Mars’ radius, almost the same as Earth’s. Experts said the discovery is very important for understanding the structure and history of Mars. But some details remain unknown, such as the exact shape and material inside the cores. Scientists added that more studies may explain how Mars lost its magnetic field.