Scientists Uncover Thick Atmosphere Surrounding Rocky ‘Super Earth’ Planet

A thick atmosphere has been identified surrounding a planet twice the size of Earth in a nearby solar system, researchers said Wednesday.

The so-called super Earth, also known as 55 Cancri e, is one of the few rocky planets outside our solar system that has a considerable atmosphere, enveloped in a layer of carbon dioxide and monoxide. The exact amounts are unclear. The Earth’s atmosphere is composed of nitrogen, oxygen, argon, and other gases.

Unlocking the Mysteries of Super Earth: What You Need to Know About 55 Cancri e

55 Cancri e is an exoplanet that orbits a Sun-like host star, 55 Cancri A. The exoplanet has a mass of about eight Earth masses and a diameter that is almost twice that of the Earth.

55 Cancri e was discovered on August 30, 2004, making it the first super-Earth discovered around a main sequence star, ahead of Gliese 876 d by a year. It is the system’s innermost planet, with orbits lasting less than 18 hours.

However, prior to the 2010 measurements and recalculations, it was assumed that this planet orbited the star every 2.8 days.

Because of its proximity to its star, 55 Cancri e is incredibly hot, with daytime temperatures topping 3,000 Kelvin. The planet’s thermal emission appears to be changeable, probably due to volcanic activity. It has been proposed that 55 Cancri e is a carbon planet.

The environment at 55 Cancri e has been extensively investigated, with varying results. Initial investigations suggested an atmosphere rich in hydrogen and helium, but later research failed to substantiate this, instead indicating an atmosphere made up of heavier molecules, potentially merely a thin atmosphere of vaporized rock.

As of 2024, JWST observations have ruled out the rock vapor atmosphere scenario, revealing evidence for a significant atmosphere rich in carbon dioxide or carbon monoxide.

Unlocking Secrets of Super-Earth: Insights into Atmosphere and Evolution

The planet’s boiling temperatures, which can reach 4,200 degrees Fahrenheit, make it unlikely to support life.

Instead, scientists think the discovery is an encouraging hint that other rocky planets with thick atmospheres may exist and be more habitable.

The exoplanet 41 light years away is eight times heavier than Earth and orbits its star Copernicus so closely that it has a perpetual day and night cycle. A light-year is approximately 6 trillion miles. Its surface is covered in magma oceans.

 

To determine the composition of its atmosphere, astronomers examined Webb Space Telescope data taken before and after the planet moved behind its star.

They split the light radiated by the planet from its star and utilized the results to compute the planet’s temperature. There is evidence that the planet’s heat was dispersed more equally across its surface, which is a common tactic for party atmospheres.

Gases from its magma oceans may play an important role in maintaining its atmospheric stability. Scientists believe that exploring this super Earth may reveal answers about how Earth and Mars evolved first with lava lakes that have since cooled.

The researchers also discovered that specific wavelengths of light were not reaching the telescope, indicating that molecules in the atmosphere were obstructing the light. Because carbon dioxide and carbon monoxide can absorb light at these specific wavelengths, the team believes the planet’s atmosphere is made up of these gases.

However, the atmosphere orbiting 55 Cancri e was most likely different in the past—the planet’s initial atmosphere would have been damaged by the heat and radiation of its host star a long time ago. Renyu Hu, a co-author of the paper and planetary scientist at NASA’s Jet Propulsion Laboratory (JPL), tells Space.com’s Robert Lea that scientists have now discovered its so-called secondary atmosphere, which is caused by gases “bubbling out” from its magma ocean.