What new class of molten planet, characterized by a permanent ocean of magma and large amounts of sulfur, was identified by University of Oxford scientists in March 2026?

In March 2026, scientists led by the University of Oxford identified a novel class of molten planet, aptly termed a "sulphurous planet." This groundbreaking discovery was made through observations of exoplanet L 98-59 d, located about 35 light-years from Earth. What sets this world apart is its defining characteristic: a vast, permanent ocean of magma beneath its surface, which is rich in sulfur. This unique composition and internal structure lead to an atmosphere laden with sulfur-bearing gases, such as hydrogen sulfide, giving it a distinctive and somewhat "stinky" signature.

Prior to this finding, astronomers would have typically categorized a planet like L 98-59 d as either a rocky "gas-dwarf" with a hydrogen atmosphere or a water-rich world with deep oceans and ice. However, data from the James Webb Space Telescope (Deals) revealed L 98-59 d's unusually low density for its size and its sulfur-rich atmosphere, challenging these traditional classifications. Computer simulations, reconstructing the planet's history over nearly five billion years, demonstrated that the enormous amounts of sulfur stored within its molten silicate mantle play a crucial role in maintaining its long-lived magma ocean and continually replenishing its thick, hydrogen-rich atmosphere.

This discovery signifies a significant expansion of our understanding of planetary diversity beyond our solar system. The ongoing chemical exchanges between the molten interior and the atmosphere of these sulphurous planets shape what telescopes observe, offering a glimpse into worlds unlike any found within our own cosmic neighborhood. While a planet like L 98-59 d is unlikely to host life due to its extreme conditions, its identification suggests that the universe may harbor an even greater variety of exotic worlds than previously imagined, prompting astronomers to reconsider existing planetary classification systems.