JWST Confirms Atmosphere on Lava Super-Earth 55 Cancri e
October 26, 2025
JWST confirms a volcanically-sustained atmosphere on lava super-Earth 55 Cancri e, reshaping planetary science.
In a groundbreaking discovery, NASA's James Webb Space Telescope has detected compelling evidence of a substantial atmosphere surrounding 55 Cancri e, a scorching hot, rocky super-Earth located 41 light-years away. This finding challenges long-held assumptions about the ability of planets orbiting extremely close to their stars to retain atmospheres and suggests a dynamic world where a molten surface may be constantly replenishing its gaseous envelope.
A Closer Look at the 'Diamond Planet'
55 Cancri e is an exoplanet of extremes. Roughly twice the diameter of Earth, it orbits its Sun-like star at a distance 70 times closer than Earth orbits the Sun, completing a year in just 18 hours. This proximity results in blistering surface temperatures hot enough to melt rock, likely shrouding the planet in an ocean of magma. Its high density has previously led scientists to theorize it could be a carbon-rich world, earning it the nickname 'the diamond planet'.
How Webb Uncovered the Atmosphere
The science team utilized JWST's powerful infrared instruments, NIRCam and MIRI, to perform secondary eclipse spectroscopy. By measuring the subtle dimming of light as 55 Cancri e passed behind its star, they were able to isolate the thermal emission from the planet's dayside. The data revealed temperatures cooler than expected for a bare, molten rock surface, which strongly implies the presence of an atmosphere that redistributes heat across the planet.
- Atmosphere Confirmed: The data provides the strongest evidence to date of a significant atmosphere on a rocky exoplanet.
- Potential Composition: Spectroscopic analysis points toward a gas-rich envelope, likely containing carbon monoxide or carbon dioxide, consistent with outgassing from a magma ocean.
- Secondary Atmosphere: This atmosphere is not primordial but 'secondary,' meaning it was generated from the planet's interior long after its formation, likely through intense, ongoing volcanic activity.
A Volcanically Forged Atmosphere
The discovery is scientifically significant because conventional wisdom suggested that intense stellar radiation and solar wind should have stripped away any atmosphere from a planet like 55 Cancri e long ago. The presence of this gaseous envelope suggests it is being actively replenished. The leading hypothesis is that the planet's magma ocean is constantly releasing dissolved gases, creating a stable, volcanically sustained atmosphere.
This discovery pushes the boundaries of our understanding of rocky exoplanets. It suggests that even the most hellish worlds can sustain atmospheres through dynamic geological processes, giving us a rare window into the early stages of terrestrial planets like Earth and Venus.
Implications and Future Research
While 55 Cancri e is definitively not habitable, studying its atmosphere provides a unique laboratory for understanding the interplay between geology and atmospheric evolution on rocky worlds. These findings will inform models of planetary formation and help astronomers refine their search for potentially habitable exoplanets by widening the scope of worlds that could retain atmospheres.
The detailed characterization of 55 Cancri e's atmosphere marks a new chapter in exoplanet science, powered by the unparalleled capabilities of the James Webb Space Telescope. It underscores how much we still have to learn about the diversity of planets in our galaxy and highlights the exciting discoveries that lie ahead.
Frequently Asked Questions
55 Cancri e is a 'super-Earth' exoplanet, about twice Earth's diameter and eight times its mass. It orbits its star in less than 18 hours, making its surface incredibly hot and likely covered in a global magma ocean.
JWST used secondary eclipse spectroscopy. It measured the planet's thermal emission (heat) as it passed behind its star. The data showed cooler-than-expected temperatures and spectral signatures indicating the presence of gases, like carbon dioxide or monoxide, which form an atmosphere.
It challenges the theory that a rocky planet this close to its star would have its atmosphere stripped away. This discovery suggests intense volcanic activity can create and sustain a 'secondary' atmosphere, opening new possibilities for atmospheric presence on extreme exoplanets.
No, 55 Cancri e is far too hot for life as we know it, with surface temperatures high enough to melt rock. However, studying its atmosphere helps scientists understand the processes that govern all rocky planets, including potentially habitable ones.