The lava world with a hydrogen-rich atmosphere and temporary clouds

Space · Published 23 October 2026 Swipe more like this →

In short: Imagine a planet so hot it remains molten, orbiting its star in less than a single day. While 55 Cancri e was once famous for being a hypothetical diamond world, new data from the James Webb Space Telescope reveals a far more complex, volcanic reality.

Located approximately 41 light years from Earth, 55 Cancri e is a super-Earth orbiting a K-type star. It is an extreme environment where the proximity to its host star—at a distance of just 0.01544 AU—generates temperatures high enough to melt rock. The planet completes a full orbit in a mere 0.7 days, a pace significantly faster than Mercury's 88-day journey around our Sun. The planet possesses a mass of about 7.99 Earths and a radius of roughly 1.875 times that of our home world. Its discovery was first announced in 2004 using the radial velocity method. This super-hot world is characterized by a global ocean of lava and sparkling skies.

Recent observations using the James Webb Space Telescope (JWST) have challenged existing models of rocky planet evolution. While scientists expected atmospheres dominated by carbon monoxide and carbon dioxide, the data revealed surprisingly large amounts of hydrogen. This suggests that the atmosphere is shaped by gases escaping from a molten interior. The study indicates that volcanic outgassing may even create temporary clouds, which could briefly cool the planet's surface before being dispersed. The research team analyzed five distinct eclipses of the planet to gather this data. These findings were submitted for publication in the journal Nature Astronomy. The variations observed between these specific events may be caused by the release of material from the planet's interior.

These findings are significant because the composition of a secondary atmosphere is directly linked to the interior redox states of the planet. By studying 55 Cancri e, astronomers can gain insights into how lava exoplanets form and evolve. Furthermore, the 55 Cancri system is expanding as researchers confirm new planets and candidates, adding complexity to one of the most well-studied exoplanet systems in our galaxy. The system is particularly notable for hosting Janssen, the planet that sparked interest due to its potential diamond composition. New confirmed planets and candidates are currently expanding the known neighborhood of this famous system. These additions provide a broader context for understanding diverse planetary architectures.

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