James Webb Space Telescope finds no atmosphere on Earth-like TRAPPIST-1 exoplanet

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The observation represents Webb's first detection of "any form of light" emitted by a rocky exoplanet.

A visualisation of the Trappist-1b exoplanet.
The Trappist-1b exoplanet is a rocky world that orbits very close to its parent star. (Image credit: NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA))

New measurements by the James Webb Space Telescope found that a rocky exoplanet orbiting a star known as TRAPPIST-1 most likely has no atmosphere. 

The finding squashes hopes that this intriguing world might host life. But don't despair — there are six more Earth-like exoplanets in the TRAPPIST-1 star system, and now that Webb has proven its ability to study them, we can hope for some more exciting news in the not so distant future.

Astronomers used the James Webb Space Telescope's Mid-Infrared Instrument (MIRI) to measure the temperature of the planet TRAPPIST-1b. Out of the seven planets that make up the TRAPPIST-1 star system, this planet orbits the closest to the parent star and is about 1.4 times as large as Earth.

Related: Webb meets the 7 intriguing exoplanets of TRAPPIST-1

The measurement, which according to the European Space Agency (ESA) represents Webb's first detection of "any form of light" emitted by a rocky exoplanet, revealed that the planet's daytime temperature was a scorching 446 degrees Fahrenheit (230 degrees Celsius). Astronomers think that's too high for the planet to have an atmosphere.

Thomas Greene, an astrophysicist in the Space Science and Astrobiology Division at NASA's Ames Research Center in California who led the observations, told Space.com in an email that he had hoped for a different result.

"Some theory groups predicted that the planet would have a dense atmosphere, while others thought it might not," Greene said. "I was more disappointed than surprised to see it had no atmosphere."

The distance between TRAPPIST-1b and its star is only about one hundredth of the sun-Earth distance. That's 40 times closer than the distance between the sun and the solar system's innermost planet Mercury. 

In this NASA digital illustration, all seven planets discovered in orbit around the red dwarf star TRAPPIST-1 are shown and could fit inside the orbit of Mercury, the innermost planet of our solar system. (Image credit: NASA via Getty Images)

Although the star at the center of the TRAPPIST-1 system is much dimmer than our sun, the planet still receives about four times as much starlight as Earth receives from the sun. Astronomers therefore didn't expect this planet to be habitable prior to ruling out the presence of an atmosphere. The observation, however, is still a breakthrough, as it shows that Webb can directly gather information about such distant Earth-like worlds. 

In the TRAPPIST-1 system, there are at least three planets — TRAPPIST-1e, 1f and 1g — that have conditions for the existence of liquid water on their surfaces and therefore might host life. 

The TRAPPIST-1 system is a hugely popular target for exoplanet research and the best explored planetary system other than our own solar system, according to NASA. Located some 40 light-years away from the sun, the star at the center of the TRAPPIST-1 system is a so-called M dwarf. Sometimes also referred to as red dwarfs, these stars are the smallest known type of stars capable of burning hydrogen in their cores. They range in size from 0.08 to 0.6 times the size of the sun and are the most numerous type of star in our galaxy, the Milky Way.

"There are about ten times as many M stars like TRAPPIST-1 than G stars like the sun," Greene wrote. "M stars are also about twice as likely to have rocky, Earth-sized planets. Therefore about 95% of the Earth-sized rocky planets in the Milky Way will have stars like TRAPPIST-1 and not like the sun."

For this reason, the TRAPPIST-1 star system is an important testbed that could help astronomers better understand where best conditions for life exist. 

Related stories:

— Exoplanets, dark matter and more: Big discoveries coming from James Webb Space Telescope, astronomers say
— James Webb Space Telescope notches 1st rocky planet confirmation
— 12 amazing James Webb Space Telescope discoveries across the universe 

Previous observations with the Hubble Space Telescope and the now retired Spitzer Space Telescope found no traces of atmospheres on any of the TRAPPIST-1 planets. However, Greene said, a possibility still exists that a very thin atmosphere surrounds TRAPPIST-1b, one that might be completely different from the atmospheres shrouding planets in the solar system. 

"We have some follow-up observations scheduled in June at another wavelength and have proposed observing a bigger part of the planet's orbit to look into and maybe rule out some other types of atmospheres," Greene said. 

The study was published in the journal Nature on Monday, March 27.

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook. 

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Tereza Pultarova
Tereza Pultarova
Senior Writer

Tereza is a London-based science and technology journalist, aspiring fiction writer and amateur gymnast. Originally from Prague, the Czech Republic, she spent the first seven years of her career working as a reporter, script-writer and presenter for various TV programmes of the Czech Public Service Television. She later took a career break to pursue further education and added a Master's in Science from the International Space University, France, to her Bachelor's in Journalism and Master's in Cultural Anthropology from Prague's Charles University. She worked as a reporter at the Engineering and Technology magazine, freelanced for a range of publications including Live Science, Space.com, Professional Engineering, Via Satellite and Space News and served as a maternity cover science editor at the European Space Agency.

19 Comments Comment from the forums
  • rod
    My observation. In the space.com article, a key comment I note. "Thomas Greene, an astrophysicist in the Space Science and Astrobiology Division at NASA's Ames Research Center in California who led the observations, told Space.com in an email that he had hoped for a different result. "Some theory groups predicted that the planet would have a dense atmosphere, while others thought it might not," Greene said. "I was more disappointed than surprised to see it had no atmosphere."

    The exoplanet atmosphere site shows TRAPPIST-1 b too. http://research.iac.es/proyecto/exoatmospheres/view.php?name=TRAPPIST-1%20b.

    This is not the first report of an exoplanet indicating no atmosphere observed. GJ 1252 b, Discovery could dramatically narrow search for space creatures, https://phys.org/news/2022-10-discovery-narrow-space-creatures.html
    Reply
  • Helio
    Yep, that's a very hot planet.
    Reply
  • rod
    There are plenty of reports out on the TRAPPIST-1, 7 exoplanet system.

    Are planets with oceans common in the galaxy? It's likely, NASA scientists find, https://phys.org/news/2020-06-planets-oceans-common-galaxy-nasa.html, "...When Webb launches, scientists will try to detect chemical signatures in the atmospheres of some of the planets in the TRAPPIST-1 system, which is 39 light years away in the constellation Aquarius. In 2017, astronomers announced that this system has seven Earth-size planets. Some have suggested that some of these planets could be watery, and Quick's estimates support this idea. According to her team's calculations, TRAPPIST-1 e, f, g and h could be ocean worlds, which would put them among the 14 ocean worlds the scientists identified in this study."

    Do the TRAPPIST-1 planets have atmospheres?, https://phys.org/news/2020-07-trappist-planets-atmospheres.html
    A review of possible planetary atmospheres in the TRAPPIST-1 system, https://arxiv.org/abs/2007.03334, 07-July-2020. “TRAPPIST-1 is a fantastic nearby (~39.14 light years) planetary system made of at least seven transiting terrestrial-size, terrestrial-mass planets all receiving a moderate amount of irradiation. To date, this is the most observationally favourable system of potentially habitable planets."

    Much hope is in the galaxy (looking for habitable exoplanets) because of TRAPPIST-1 exoplanet system. Much remains to be confirmed and shown true about those exoplanets as well.
    Reply
  • Helio
    Yes. With oxygen being the most produced "metal" (nucleosynthesis), it makes sense that water is abundant. Oxygen is about 10x more abundant than iron.

    Trappist-1e seems favorable, though it didn't make the list using the atmospheric method.
    Reply
  • rod
    Helio in post #5 points out the hope in the galaxy :) for the TRAPPIST-1 system. Atmospheric studies by JWST of exoplanets, continues to present surprises and evolutionary model problems.

    James Webb Space Telescope confirms giant planet atmospheres vary widely, https://phys.org/news/2023-03-james-webb-space-telescope-giant.html
    Ref - High atmospheric metal enrichment for a Saturn-mass planet, https://www.nature.com/articles/s41586-023-05984-y, 27-March-2023.

    It remains to be seen just how many *rocky* exoplanets have no atmospheres, and how many gas giant exoplanets depart from the solar system model standard. As the phys.org report concludes: "While an abundance of carbon might seem favorable for chances of life, a high carbon to oxygen ratio actually means less water on a planet or in a planetary system—a problem for life as we know it. Smertrios is an interesting first case of atmospheric composition for this particular study, said Lunine, who has plans in place to observe five more giant exoplanets in the coming year using JWST. Many more observations are needed before astronomers can discover any patterns among giant planets or in systems with multiple giant planets or terrestrial planets to the compositional diversity astronomers are beginning to document. "The origin of this diversity is a fundamental mystery in our understanding of planet formation," Bean said. "Our hope is that further atmospheric observations of extrasolar planets with JWST will quantify this diversity better and yield constraints on more complex trends that might exist."
    Reply
  • mbee1
    Admin said:
    New measurements by the James Webb Space Telescope found that a rocky exoplanet orbiting a star known as TRAPPIST-1 most likely has no atmosphere.

    James Webb Space Telescope finds no atmosphere on Earth-like TRAPPIST-1 exoplanet : Read more
    One has to wonder what got lost between the actual study and the author of this piece. Venus has a surface temperature of 900 degrees and a very dense atmosphere. All the study would seem to indicate is the atmosphere is not as thick as Venus depending on were the temperature measurements were made. If at the surface we could have an atmosphere as thick as earths and measure that same result. 100% that same result if it is as thin as Mars. Since the planet is 1.4 times more massive than earth the likelihood of zero atmosphere is essentially zero if one looks at the earth system for examples. The only way to arrive at zero atmosphere is if the sun has had a massive higher output in the past, perhaps a flare star history, no such history is mentioned in the article.
    Reply
  • rod
    JWST reports the temperature of TRAPPIST-1 b is 503 K now, previous reporting showed 400 K. JWST not only shows no atmosphere or little, but also increased the exoplanet temperature from 400 K to 503 K. Exoplanet studies can turn around quickly when looking for habitable exoplanets. At present, the Earth is very rare with abundant water, abundant life living today, and a fossil record when compared to other planets in our solar system or the more than 5300 exoplanets documented now.

    Webb measures temperature of rocky exoplanet for first time, https://phys.org/news/2023-03-webb-temperature-rocky-exoplanet.html
    ref - Thermal Emission from the Earth-sized Exoplanet TRAPPIST-1 b using JWST, https://www.nature.com/articles/s41586-023-05951-7, 27-March-2023.

    My note. http://exoplanet.eu/catalog/trappist-1_b/, shows the measured temperature is 503 K citing Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST, https://arxiv.org/abs/2303.14849, 26-March-2023. The calculated temperature was 400 K so JWST increased the exoplanet temperature by 100 K. This site still reports 400 K, JWST has changed this view of TRAPPIST-1 b exoplanet. http://research.iac.es/proyecto/exoatmospheres/view.php?name=TRAPPIST-1%20b
    Reply
  • murgatroyd
    From what I understand, even the $10 billion Webb telescope isn't likely to find evidence of life on exoplanets. That will be the task of a future telescope, capable of performing spectroscopic examination on a very large number of rocky planets in habitable zones. A clear marker of biological activity would be detection of chlorophyll. A null result after examination of, say, 100,000 candidate planets would be disheartening, but at the same time provide clarity. In a galaxy with some 100 billion stars, there could still be life elsewhere ... but given the gulfs in distance and time, it could be an academic question, of no relevance to humans.

    In the very distant future, our "descendants" (for certain values of the word) could still explore the length and breadth of the Milky Way, but they will either be purely mechanical embodiments of artificial general intelligence ... or genetically engineered organisms capable of withstanding millenniae of interstellar travel. If the latter, my money is on cognitively enhanced tardigrades. These tiny animals (please don't call them ugly!) are already famed today for resilience and longevity in the harshest conditions including airlessness, radioactivity and cold. Perhaps a smattering of human DNA will be preserved in the genome of the tardigrades-plus (for sentimental reasons).
    Reply
  • rod
    Interesting view by murgatroyd in post #9. The tardigrades look like a problem now for panspermia doctrine.

    Tardigrades survive impacts of up to 825 meters per second, https://phys.org/news/2021-05-tardigrades-survive-impacts-meters.html
    "To find out, the research pair obtained 20 tardigrade specimens and put them in a deep freeze to induce their sleep-like state. They then placed them in groups of two or three into thin cylinders filled with water. The cylinders were then placed inside of a larger cylinder that served as an ammunition shell for a two-stage light gas gun. The gun was placed inside of a vacuum chamber where its shell was fired at a target made of sand. Shots were fired from the gun at different speeds to see what impact each would have on the passenger tardigrades. The researchers found that the tardigrades shot from the gun at speeds up to 825 meters per second could be resuscitated after removal from the cylinder. Those experiencing higher-speed impacts were torn apart and did not survive. The researchers suggest that tardigrades would likely not survive an impact with a planet if they traveled across space on an asteroid (as some have suggested), as such impacts tend to be at higher speeds than the tardigrades could tolerate."

    My observation. This is a blow to panspermia thinking and life transferring around to other planets via asteroid and meteor impacts. Velocities and kinetic energy too high for survival of tardigrades.
    Reply
  • Helio
    rod said:
    JWST reports the temperature of TRAPPIST-1 b is 503 K now, previous reporting showed 400 K. JWST not only shows no atmosphere or little, but also increased the exoplanet temperature from 400 K to 503 K. Exoplanet studies can turn around quickly when looking for habitable exoplanets. At present, the Earth is very rare with abundant water, abundant life living today, and a fossil record when compared to other planets in our solar system or the more than 5300 exoplanets documented now.
    It's nice to see the JWST is working as hoped. It offers better accuracy than prior scopes.

    The methods used to calculate temperatures for planets is subject to how accurate the input data is. The equilibrium temp. method, for example, assumes a bond albedo of 0.3 for the planet, which is just a guess. A lower albedo would make the planet more likely to be hotter.

    Another method uses the radius of the star, which can't be determined to great accuracy since most stars can't even be seen as anything other than a tiny point.

    For this reason, I like to show where in the HZ a planet is calculated to be, thus one can play with the probability a little better when knowing if it's in the middle of the zone or on the edge.
    Reply