For years, astronomers have been on the quest to locate rocky exoplanets beyond our solar system boasting atmospheres—an essential criterion for potential habitability. Finally, their perseverance seems to have paid off, albeit with a disheartening twist. The latest discovery reveals a super-Earth, a rocky giant larger than our planet but smaller than Neptune, orbiting precariously close to a star slightly dimmer and less massive than our sun. Clocking an orbit of approximately 18 hours, this hellish planet presents a surface resembling molten rock, extinguishing any hope for sustaining life.
Recently unveiled through infrared observations facilitated by the James Webb Space Telescope, this infernal realm, dubbed 55 Cancri e or Janssen, showcases an atmosphere of considerable proportions, albeit unwelcomingly inhospitable. Planetary scientist Renyu Hu, spearheading the study published in Nature, suggests the atmosphere may be inundated with carbon dioxide, carbon monoxide, water vapor, and sulfur dioxide, although its precise composition remains elusive. Moreover, the thickness of this atmospheric veil remains ambiguous, with speculations ranging from Earth-like to potentially denser than Venus, our solar system's most suffocating atmosphere.
55 Cancri e, a behemoth about 8.8 times the mass of Earth with twice its diameter, orbits its host star at a mere fraction of the distance between Mercury and the sun, resulting in scorching surface temperatures surpassing 3,000 degrees Fahrenheit. Astrophysicist Brice-Olivier Demory of the University of Bern aptly remarks, "Indeed, this is one of the hottest-known rocky exoplanets," suggesting that in the vast expanse of our galaxy, there exist far more inviting destinations for cosmic voyages.
Odds are that 55 Cancri e is tidally locked, presenting the same face to its star perpetually, akin to the moon's relationship with Earth. Situated approximately 41 light-years away in the constellation Cancer within the Milky Way, this rocky inferno shares its stellar neighborhood with four gas giants, orbiting a binary system alongside a diminutive red dwarf star.
Despite the initial excitement surrounding the discovery of an atmosphere-enveloped rocky exoplanet, the harsh realities of its environment dash hopes of habitability. The searing proximity to its star renders any prospects for liquid water—a fundamental requirement for life—impossible. Moreover, the planet's atmospheric persistence defies conventional expectations, with gases from a purported ocean of magma continually replenishing its veil against stellar erosion and winds.
While this revelation marks a milestone in exoplanetary exploration, underscoring the potential of the James Webb Space Telescope, it also emphasizes the long road ahead. Unlike Earth, where the atmosphere nurtures life, shields against radiation, and sustains vital conditions for water, 55 Cancri e serves as a sobering reminder of the intricate balance necessary for habitability. As Demory reflects, "This result on 55 Cnc e entertains the hope that Webb could conduct similar investigations on planets that are much cooler than 55 Cnc e, which could support liquid water at their surface. But we are not there yet."
