Scientists detect atmosphere on distant rocky exoplanet

This artist's concept shows what the exoplanet 55 Cancri e could look like. Credit: University of Bern/Switzerland.

Researchers using the James Webb Space Telescope have made a significant breakthrough by potentially detecting an atmosphere on 55 Cancri e, a rocky exoplanet 41 light-years away from Earth.

This finding, considered the best evidence yet of an atmosphere around a rocky planet outside our solar system, could deepen our understanding of planetary science.

The results of this study were recently published in the journal Nature.

55 Cancri e, which is nearly twice the size of Earth but with a slightly higher density, orbits a sun-like star in the constellation Cancer.

It is part of a planetary system that includes four other planets. This planet is a type known as a super-Earth, meaning it is larger than Earth but smaller than ice giants like Neptune.

Brice-Olivier Demory from the University of Bern, along with an international team of researchers, has been studying this planet extensively.

The new observations from the James Webb Space Telescope (JWST) have revealed surprising details about 55 Cancri e, suggesting it might have an atmosphere despite its harsh conditions.

Traditionally, the surface of 55 Cancri e is thought to be an extreme environment with temperatures high enough to maintain a sea of magma.

It orbits very close to its star, completing one orbit in just 18 hours, which likely means it is tidally locked—always showing the same face to its star.

These factors have made scientists skeptical about the presence of a traditional atmosphere because the intense heat and radiation from the nearby star would typically strip it away.

However, the recent data from JWST has challenged these assumptions. The telescope measured the infrared light emitted by the planet, which provides clues about its temperature. The findings showed that the dayside of the planet, the side facing the star, has a temperature of about 1500 degrees Celsius, which is cooler than expected if the planet had no atmosphere at all.

This lower temperature suggests that an atmosphere could be present, likely a “secondary atmosphere” created from volcanic activity and gases released from the planet’s molten surface.

Such an atmosphere, rich in volatiles like carbon dioxide or carbon monoxide, could help transfer heat from the dayside to the dark side of the planet, explaining the unexpected temperature readings.

Renyu Hu from NASA’s Jet Propulsion Laboratory, who led the research team, explains that this atmosphere could be playing a crucial role in cooling the planet by absorbing and redistributing thermal energy. Without it, the planet’s surface would likely be much hotter.

Although 55 Cancri e is far from habitable by any standards known to us, studying its atmosphere and environmental dynamics can provide valuable insights into the processes that might affect rocky planets closer to home, including early Earth, Venus, and Mars, which are believed to have once harbored magma oceans.

This research not only showcases the capabilities of the James Webb Space Telescope in studying distant planets but also opens new avenues in understanding how atmospheres can exist and affect conditions on rocky planets outside our solar system.