Recent seismic studies from NASA’s InSight mission indicate Mars has a liquid outer core and evidence now points to a smaller solid inner core, meaning the planet’s interior shows both liquid and solid layers that drive internal dynamics
Observations from missions
Seismic data recorded by NASA’s InSight lander, including waves from deep marsquakes that penetrated to the planet’s centre, provide the clearest measurements to date of Mars’s internal structure and reveal a liquid layer consistent with a molten outer core surrounded by a solid component.
Why it looks blue
Mars’s partly liquid core arises because its composition and thermal history differ from Earth’s: a core rich in iron mixed with lighter elements such as sulfur and oxygen can remain molten in an outer shell while cooling can allow a small solid inner kernel to form, producing the observed seismic signatures.
Recent evidence and imagery
Analyses published from InSight’s seismic records used waves that passed through the deep interior to constrain core size, state and density; these results show a denser, smaller liquid outer core than earlier models predicted and support the detection of a compact solid inner core in newer studies.
Implications for science
A partly liquid core implies Mars retained internal heat long enough for complex internal dynamics, which affects past magnetic field generation, volcanic history and long‑term thermal evolution, and improves models of how terrestrial planets form and cool.
Takeaway
Evidence that Mars has both liquid and solid core layers transforms our picture of the planet’s interior, offering new insights into its geological past and informing where to look for clues about ancient habitability and the processes that shaped the Red Planet.