What type of new, low-density exoplanet, about 1.6 times the size of Earth, was identified in March 2026 by researchers using the James Webb Space Telescope?

Astronomers have recently identified a fascinating new class of exoplanet, one that is best described as a molten planet. This intriguing discovery, made in March 2026 by researchers utilizing the advanced capabilities of the James Webb Space Telescope (Deals), concerns an exoplanet designated L 98-59 d. What makes this world so unique is its surprisingly low density despite being roughly 1.6 times the size of Earth, along with evidence suggesting it harbors a vast, permanent underground ocean of magma.

This new classification stems from observations that revealed significant amounts of hydrogen sulfide in the exoplanet's atmosphere. Combined with its unusual density, this atmospheric composition points to a world whose interior is largely composed of molten rock, or silicate lava, akin to a global magma ocean. Unlike Earth, which cooled to form a solid crust, L 98-59 d appears to have maintained this molten state for much of its five-billion-year history, trapping enormous quantities of sulfur beneath its surface.

The discovery of this molten planet challenges previous astronomical classifications for small exoplanets, which typically categorized them as either rocky gas dwarfs with hydrogen-rich atmospheres or water-rich worlds dominated by deep oceans and ice. L 98-59 d, located about 35 light-years from Earth and orbiting a small red star, simply doesn't fit neatly into either of these established categories. This finding highlights the incredible diversity of worlds beyond our solar system and underscores the James Webb Space Telescope's crucial role in expanding our understanding of planetary formation and evolution.