Scientists announced on Wednesday, September 3, 2025, that Mars has a solid inner core made mostly of metal, similar to Earth’s. The finding came from seismic records collected by NASA’s InSight lander, which detected over 1,300 marsquakes before ending operations in 2022. The spacecraft had landed on a plain near Mars’ equator in 2018. Earlier studies suggested that the center of Mars was liquid, but new research shows a solid inner core surrounded by molten material. According to the journal Nature, the solid section extends about 380 miles (613 kilometers) from the center. It is likely formed of iron and nickel, with lighter elements such as oxygen possibly included. The liquid outer core is larger, reaching up to 1,100 miles (1,800 kilometers). Scientists added that crystallization inside the solid core may have started long ago and may still continue today.

The study focused on 23 marsquakes with epicenters located between 1,200 and 2,360 kilometers from the lander. The evidence indicated that the solid inner core makes up about one-fifth of Mars’ radius, a ratio similar to Earth’s. Experts described the results as groundbreaking, giving clearer comprehension of the planet’s structure and history. However, questions remain about the exact shape and composition of the core. Specialists said more seismic data is needed to solve mysteries such as “mushy zones” in the outer core. Further modeling may explain how the inner core developed and why Mars lost its magnetic field.