As Never Seen Before: NASA’s Webb Reveals an Exoplanet Unlike Any in Our Solar System

Exoplanet WASP-39 b Illustration

Exoplanet WASP-39 b Illustration. Credit: Melissa Weiss/Center for Astrophysics | Harvard & Smithsonian

Observations of Exoplanet WASP-39b show fingerprints of atoms and molecules, as well as signs of active chemistry and clouds.

WASP-39 b is a planet unlike any in our solar system – a Saturn-sized behemoth that orbits its star closer than Mercury is to our Sun. When NASA’s James Webb Space Telescope initially began regular science operations, this exoplanet was one of the first to be examined. The exoplanet science community is buzzing with excitement over the results. Webb’s incredibly sensitive instruments have provided a profile of WASP-39 b’s atmospheric constituents and identified a plethora of contents, including water, sulfur dioxide, carbon monoxide, sodium, and potassium. The findings bode well for the capability of Webb’s instruments to conduct a broad range of investigations of all types of exoplanets, including small, rocky worlds like those in the TRAPPIST-1 system.

Exoplanet WASP-39 b and Star

This illustration shows what exoplanet WASP-39 b could look like, based on the current understanding of the planet. WASP-39 b is a hot, puffy gas giant with a mass 0.28 times Jupiter (0.94 times Saturn) and a diameter 1.3 times greater than Jupiter, orbiting just 0.0486 astronomical units (4,500,000 miles) from its star. The star, WASP-39, is fractionally smaller and less massive than the Sun. Because it is so close to its star, WASP-39 b is very hot and is likely to be tidally locked, with one side facing the star at all times. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

NASA’s Webb Space Telescope Reveals an Exoplanet Atmosphere as Never Seen Before

Another first was just scored by NASA’s James Webb Space Telescope: a molecular and chemical profile of a distant world’s skies.

While Webb and other space telescopes, including NASA’s Hubble and Spitzer, previously have revealed isolated ingredients of this broiling planet’s atmosphere, the new readings from Webb provide a full menu of atoms, molecules, and even signs of active chemistry and clouds.

“Data like these are a game changer.” — Natalie Batalha

A hint of how these clouds might look up close is also provided by the latest data: they are likely broken up rather than a single, uniform blanket over the planet.

The telescope’s array of highly sensitive instruments was trained on the atmosphere of WASP-39 b, a “hot Saturn” (a planet about as massive as Saturn but in an orbit tighter than Mercury) orbiting a star some 700 light-years away.

The findings bode well for the capability of Webb’s instruments to conduct the broad range of investigations of all types of exoplanets – planets around other stars – hoped for by the science community. That includes probing the atmospheres of smaller, rocky planets like those in the TRAPPIST-1 system.

“We observed the exoplanet with multiple instruments that, together, provide a broad swath of the infrared spectrum and a panoply of chemical fingerprints inaccessible until [this mission],” said Natalie Batalha. “Data like these are a game changer.” Batalha is an astronomer at the University of California, Santa Cruz, who contributed to and helped coordinate the new research.

Exoplanet WASP-39 b (Webb Transmission Spectra)

The atmospheric composition of the hot gas giant exoplanet WASP-39 b has been revealed by NASA’s James Webb Space Telescope. This graphic shows four transmission spectra from three of Webb’s instruments operated in four instrument modes. A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves in front of the star, to the unfiltered starlight detected when the planet is beside the star. Each of the data points (white circles) on these graphs represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. At upper left, data from NIRISS shows fingerprints of potassium (K), water (H2O), and carbon monoxide (CO). At upper right, data from NIRCam shows a prominent water signature. At lower left, data from NIRSpec indicates water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO). At lower right, additional NIRSpec data reveals all of these molecules as well as sodium (Na). Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

The suite of discoveries is detailed in a set of five new scientific papers, three of which are in press and two of which are under review. Among the unprecedented revelations is the first detection in an exoplanet atmosphere of sulfur dioxide (SO2), a molecule produced from chemical reactions triggered by high-energy light from the planet’s parent star. On Earth, the protective ozone layer in the upper atmosphere is created in a similar way.

“This is the first time we see concrete evidence of photochemistry – chemical reactions initiated by energetic stellar light – on exoplanets,” said Shang-Min Tsai, a researcher at the University of Oxford in the United Kingdom and lead author of the paper explaining the origin of sulfur dioxide in WASP-39 b’s atmosphere. “I see this as a really promising outlook for advancing our understanding of exoplanet atmospheres with [this mission].”

“We had predicted what [the telescope] would show us, but it was more precise, more diverse, and more beautiful than I actually believed it would be.” — Hannah Wakeford

This led to another first: scientists applying computer models of photochemistry to data that requires such physics to be fully explained. The resulting improvements in modeling will help build the technological know-how to interpret potential signs of habitability in the future.

“Planets are sculpted and transformed by orbiting within the radiation bath of the host star,” Batalha said. “On Earth, those transformations allow life to thrive.”

The planet’s proximity to its host star – eight times closer than Mercury is to our Sun – also makes it a laboratory for studying the effects of radiation from host stars on exoplanets. Better knowledge of the star-planet connection should bring a deeper understanding of how these processes affect the diversity of planets observed in the galaxy.

To see light from WASP-39 b, Webb tracked the planet as it passed in front of its star, allowing some of the star’s light to filter through the planet’s atmosphere. Different types of chemicals in the atmosphere absorb different colors of the starlight spectrum, so the colors that are missing tell astronomers which molecules are present. By viewing the universe in infrared light, Webb can pick up chemical fingerprints that can’t be detected in visible light.

Other atmospheric constituents detected by the Webb telescope include sodium (Na), potassium (K), and water vapor (H2O), confirming previous space- and ground-based telescope observations as well as finding additional fingerprints of water, at these longer wavelengths, that haven’t been seen before.

Webb also saw carbon dioxide (CO2) at higher resolution, providing twice as much data as reported from its previous observations. Meanwhile, carbon monoxide (CO) was detected, but obvious signatures of both methane (CH4) and hydrogen sulfide (H2S) were absent from the Webb data. If present, these molecules occur at very low levels.

To capture this broad spectrum of WASP-39 b’s atmosphere, an international team numbering in the hundreds independently analyzed data from four of the Webb telescope’s finely calibrated instrument modes.

“We had predicted what [the telescope] would show us, but it was more precise, more diverse, and more beautiful than I actually believed it would be,” said Hannah Wakeford, an astrophysicist at the University of Bristol in the United Kingdom who investigates exoplanet atmospheres.

Having such a complete roster of chemical ingredients in an exoplanet atmosphere also gives scientists a glimpse of the abundance of different elements in relation to each other, such as carbon-to-oxygen or potassium-to-oxygen ratios. That, in turn, provides insight into how this planet – and perhaps others – formed out of the disk of gas and dust surrounding the parent star in its younger years.

WASP-39 b’s chemical inventory suggests a history of smashups and mergers of smaller bodies called planetesimals to create an eventual goliath of a planet.

“The abundance of sulfur [relative to] hydrogen indicated that the planet presumably experienced significant accretion of planetesimals that can deliver [these ingredients] to the atmosphere,” said Kazumasa Ohno, a UC Santa Cruz exoplanet researcher who worked on Webb data. “The data also indicates that the oxygen is a lot more abundant than the carbon in the atmosphere. This potentially indicates that WASP-39 b originally formed far away from the central star.”

In so precisely parsing an exoplanet atmosphere, the Webb telescope’s instruments performed well beyond scientists’ expectations – and promise a new phase of exploration among the broad variety of exoplanets in the galaxy.

“We are going to be able to see the big picture of exoplanet atmospheres,” said Laura Flagg, a researcher at Cornell University and a member of the international team. “It is incredibly exciting to know that everything is going to be rewritten. That is one of the best parts of being a scientist.”

The James Webb Space Telescope is the most powerful space telescope ever constructed and the world’s premier space science observatory. It will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

20 Comments on "As Never Seen Before: NASA’s Webb Reveals an Exoplanet Unlike Any in Our Solar System"

  1. It’s hardly “in our solar system”…really? You’d think a basic understanding is required to write an article of this nature

    • Read the title again. It says “…unlike in our solar system”. You left out the key word “unlike”.

      • That’s pretty funny. I misunderstood it as well. That’s why it’s always good to have a second pair of eyes. 🙂 Thanks for the correction.

  2. It’s 2022 and still we have artists’ impressions. Meh. Fix Earth first, maybe.

  3. I dont think you understand what solar system means…

  4. No real pics please? No wonder people still think the earth is flat…get some pics and then write this please?

    • What do you mean by “real pics”? JWST is an infra-red telescope with infra-red spectrometry. You get splotches and graphs. Those give way more information than a photo of a miniscule bright dot touching a tiny bright dot.

  5. Julius Mazzarella | November 23, 2022 at 3:55 pm | Reply

    Were getting warmer …carbon monoxide and sulfur dioxide. I used to make that in my vintage chemistry set back in the day. It’s the one with the rotten egg smell. I think Mr. Webb is going to have to sample more real estate. This one doesn’t fit the bill yet.

  6. "Gus" the family dog | November 23, 2022 at 5:25 pm | Reply

    In other news… potentially habitable exoplanets will never be reachable to sustain human life.

    Enjoyable reading none the less.

    • Any prediction that has “never” in it will always be proven wrong. Never is an effing long time.
      – TheHeck, 2022

  7. I think the title was carefully chosen to make it sound like the exoplanet was in our solar system aystem. I’m pretty sure most exoplanets discovered are “unlike any in our solar system”

    • First, if it were in our solar system, it won’t be an exoplanet.

      Second, practically all exoplanets discovered up to now have been very different from what we see in our solar system, because the technology that we have today is skewed towards capturing extremes. Both the luminosity dip method and the gravitational wobble method are better at capturing massive planets. Since we don’t have the patience to observe same star over long periods of time, we are better at discovering planets with short orbital periods (ie. very close to their star).

      So we are biased towards hot Jupiters, hot Saturns, hot Neptunes and hot Super Earths. With the technology that we have, if we look at the solar system from 10 LY away, we probably won’t detect anything.

  8. Read the comment again please. You totally misunderstood it.

  9. The Heck, it looks like many who replied negatively may not be regular subscribers to Physics Today or other any science subscriptions. I’m not sure if you could have explained the discovery anymore clearly. Thank you for sharing and don’t let snarky comments deter your publishing.

  10. The heck. Seems like you live a miserable life. Why dont you sit down while the adults do the talking. sorry your so mean. Smile ok. It’ll prob help your ego out. Bye bye now smh.

  11. That was a great article. When we look at things either extremely small or extremely far away, pictures become less and less meaningful or possible. Visible light can only be resolved to a limited degree and a “picture” cannot be formed but the data contained in the light can still be gleaned. You will just have to be satisfied with the artist’s impression.

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