The search for a rocky world shrouded in a protective atmosphere somewhere else in space has eluded scientists, but the James Webb Space Telescope has found a compelling case.
Webb, the lead infrared observatory for NASA and the European and Canadian space agencies, has taken a closer look at super-Earth 55 Cancri e, an exoplanet just 41 light-years away that is covered in either carbon dioxide or carbon monoxide.
But calling it an “Earth-like world” would be misleading. Discovered 13 years ago in the constellation Cancer, the planet appears to orbit so close to its star that its surface is likely made of lava. And because it hugs the star so tightly, it’s likely that it doesn’t rotate either, leaving one side in constant darkness.
Still, the discovery may be the best evidence scientists have ever found of the atmosphere of a rocky planet outside Earth’s solar system. One such finding was published in the journal Naturestrengthens the experts’ confidence that they will eventually discover rocky worlds with a hospitable atmosphere.
“Webb is pushing the boundaries of exoplanet characterization on rocky planets,” Renyu Hu, a researcher at NASA’s Jet Propulsion Laboratory, said in a statement. “It really enables a new kind of science.”
Webb may have just found an Earth-like world with an atmosphere
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When exoplanets cross in front of their parent star, the star’s light is filtered through this atmosphere. Molecules in the atmosphere absorb certain wavelengths or colors of light. By splitting the star’s light into its basic components – a rainbow – astronomers can use Webb to see which segments of light are missing and see the molecular makeup of an atmosphere.
Destructible speed of light
Scientists have found signs of atmospheres around many exoplanets over the past 20 years, but all were gas giant planets like Jupiter, whose thick atmospheres were mostly made of hydrogen.
It is important to know what is in the atmosphere of another planet. NASA has jokingly referred to Earth’s atmosphere as its “security blanket”: without it, there would be no life thriving on the planet. This cocoon keeps oxygen in the air and filters out the sun’s harmful ultraviolet radiation while keeping our world warm and habitable. In addition, a pressure is created that allows liquid water to exist on the earth’s surface.
NASA has created a travel poster-inspired illustration of what the exoplanet 55 Cancri e might look like.
Image credit: NASA / JPL-Caltech
The first indication that 55 Cancri e may have a significant atmosphere came from temperature measurements based on the infrared light it emitted. If the planet is covered in dark molten rock with no atmosphere—or with a very thin atmosphere of vaporized rock—the side of constant light should be about 4,000 degrees Fahrenheit.
Instead, the researchers found a much lower temperature of about 2,800 degrees Fahrenheit.
“Webb is pushing the boundaries of exoplanet characterization on rocky planets,” said Renyu Hu, a researcher at NASA’s Jet Propulsion Laboratory.
Image credit: NASA GSFC/CIL/Adriana Manrique Gutierrez Illustration
“This is a very strong indication that the energy is distributed from the day side to the night side, most likely through a volatile atmosphere,” Hu said.
While 55 Cancri e appears far too hot to support life as we know it, scientists believe studying it could improve their understanding of the primordial conditions on Earth, Venus and Mars, which some believe they were once also covered by magma oceans.
“Ultimately, we want to understand what conditions allow a rocky planet to maintain a gas-rich atmosphere: a key component for a habitable planet,” Hu said.