Scientists announced Wednesday, September 3, 2025, that Mars has a solid inner core composed mainly of metal, similar to Earth’s. Evidence was gathered through seismic records taken by NASA’s InSight lander, which registered more than 1,300 marsquakes before stopping operations in 2022. In 2018, the spacecraft arrived on a wide plain near the equator of Mars. Previous research had proposed that the core was liquid, but current evidence reveals a solid inner section encircled by molten material. According to research published in Nature, the solid section extends 380 miles (613 kilometers) from the planet’s center. It is likely made of iron and nickel, possibly enriched with lighter elements such as oxygen. The liquid outer core is larger, stretching to about 1,100 miles (1,800 kilometers). Scientists added that crystallization inside the core may have begun long ago and may still be happening today.

The study relied mainly on 23 marsquakes with epicenters located between 1,200 and 2,360 kilometers from the lander. Evidence suggested that the inner core of Mars accounts for roughly one-fifth of the planet’s radius, a proportion comparable to Earth’s. Experts described the results as groundbreaking, offering deeper comprehension of Mars’ structure and its evolution. However, uncertainties remain about the exact shape and composition of the inner and outer cores. Specialists noted that without new seismic data, some mysteries, such as possible “mushy zones” within the outer core, cannot be clarified. Additional modeling may illuminate how the inner core formed and what it reveals about the planet’s lost magnetic field. This absence, possibly caused by slow crystallization, remains a scientific enigma.