Astronomers have achieved a significant breakthrough by detecting the first rocky exoplanet with a substantial atmosphere. The planet, known as 55 Cancri e or Janssen, offers invaluable insights into planetary formation and atmospheric evolution, despite its inhospitable conditions.
Located about 41 light-years away in the constellation Cancer, 55 Cancri e is a “super-Earth”—a rocky world larger than Earth but smaller than Neptune. It orbits extremely close to its star, completing a full orbit in just 18 hours. This proximity results in scorching surface temperatures around 1,725 degrees Celsius, rendering it uninhabitable.
Infrared observations using the James Webb Space Telescope revealed the presence of a significant atmosphere, likely rich in carbon dioxide or carbon monoxide, and possibly containing water vapor and sulfur dioxide. Planetary scientist Renyu Hu of NASA’s Jet Propulsion Laboratory and Caltech explained that the atmosphere may be continuously replenished by gases released from a vast ocean of molten rock on the planet’s surface.
“The discovery of an atmosphere on 55 Cancri e pushes the boundaries of our understanding of exoplanetary atmospheres and their compositions,” Hu stated. “While the planet itself is too hot to sustain life, studying its atmosphere provides valuable data on atmospheric formation and evolution in extreme conditions.”
Astrophysicist Brice-Olivier Demory of the University of Bern highlighted the importance of this finding for future research. “This breakthrough entertains the hope that the James Webb Space Telescope could conduct similar investigations on cooler planets that might support liquid water,” Demory said. “Though 55 Cancri e is not suitable for life, it paves the way for discovering more Earth-like exoplanets.”
The detection marks a milestone in astronomy, as previous atmospheric observations were limited to gas giants. The ability to identify atmospheres on rocky exoplanets opens new avenues for understanding the diversity of planets in our galaxy and assessing their potential habitability.
