Lava planets are rocky exoplanets that orbit so close to their host star that their dayside is hot enough to melt silicate rock.
Boukaré et al. introduce a simple theoretical framework to describe the evolution of the coupled interior-atmosphere system of lava planets. Image credit: Sci.News.
Lava planets are Earth- to super-Earth-sized worlds orbiting extremely close to their host stars, completing an orbit in less than a single Earth day.
Much like Earth’s Moon, they are expected to be tidally locked, always showing the same face to their star.
Their dayside surfaces reach such extreme temperatures that silicate rocks melt — and even vaporize — creating conditions unlike anything in our Solar System.
These exotic worlds, easily observable due to their ultrashort orbital period, provide unique insights into the fundamental processes that shape planetary evolution.
“Lava planets are in such extreme orbital configurations that our knowledge of rocky planets in the Solar System does not directly apply, leaving scientists uncertain about what to expect when observing lava planets,” said Dr. Charles-Édouard Boukaré, a researcher at York University.
“Our simulations propose a conceptual framework for interpreting their evolution and provide scenarios to probe their internal dynamics and chemical changes over time.”
“These processes, though greatly amplified in lava planets, are fundamentally the same as those that shape rocky planets in our own Solar System.”
When rocks melt or vaporize, elements such as magnesium, iron, silicon, oxygen, sodium, and potassium partition differently between vapor, liquid, and solid phases.
The unique orbital configuration of lava planets maintains vapor-liquid and solid-liquid equilibria over billions of years, driving long-term chemical evolution.
Using unprecedented numerical simulations, the authors predict two end-member evolutionary states:
(i) fully molten interior (likely young planets): the atmosphere mirrors the bulk planetary composition, and heat transport within the molten interior keeps the nightside surface hot and dynamic;
(ii) mostly solid interior (likely older planets): only a shallow lava ocean remains on the dayside, and the atmosphere becomes depleted in elements such as sodium, potassium, and iron.
“We really hope we can observe and distinguish old lava planets from young lava planets with the NASA/ESA/CSA James Webb Space Telescope,” Dr. Boukaré said.
“If we can do this, it would mark an important step toward moving beyond the traditional snapshot view of exoplanets.”
The study was published today in the journal Nature Astronomy.
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CÉ. Boukaré et al. The role of interior dynamics and differentiation on the surface and in the atmosphere of lava planets. Nat Astron, published online July 29, 2025; doi: 10.1038/s41550-025-02617-4