Astronomers have identified an extraordinary exoplanet in a nearby region of the Milky Way, revealing a hostile world dominated by a vast ocean of molten rock and a toxic, sulfur-rich atmosphere.
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The planet, L 98-59 d, lies about 34 light-years from Earth in the Volans constellation and orbits a dim red dwarf star. Although its diameter is more than 60% larger than Earth’s, its density is significantly lower, suggesting a very different internal structure.
Researchers found that the planet lacks distinct layers such as a crust or mantle. Instead, it is composed of a deep, churning magma ocean that makes up as much as 70–90% of its interior. This molten layer stretches thousands of kilometres deep, with only a relatively small metallic core at its centre.
The study, published in Nature Astronomy, highlights the extreme conditions on the planet. Its thick atmosphere is dominated by hydrogen but contains a high concentration of sulfur compounds, including hydrogen sulfide — a gas known for its strong “rotten egg” smell. This toxic mix has triggered a runaway greenhouse effect, trapping heat and keeping surface temperatures above 1,500°C.
The exoplanet was first discovered in 2019 and later studied using the James Webb Space Telescope along with ground-based observatories. Scientists used advanced simulations to trace its evolution over nearly five billion years.
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Unlike many molten worlds that are heated primarily by their proximity to their stars, researchers say the extreme conditions on L 98-59 d are maintained by a combination of atmospheric chemistry, stellar radiation, and gravitational interactions with neighboring planets.
With more than 6,100 exoplanets discovered so far, scientists say this unique world stands apart — offering new insights into planetary formation, but little hope for life.