The powerful Webb telescope doesn’t need to take pretty pictures to radically change our grasp of the cosmos.
Astronomers focused the space observatory — which this year successfully reached its outpost a million miles from Earth — on the Saturn-like exoplanet (meaning planet outside our solar system) WASP-39 b. It is a hot gas giant closely orbiting a star at a distance of 700 light years. Previously, scientists used specialized instruments aboard Webb to detect the gas carbon dioxide on this extreme world.
Now, for the first time, they’ve discovered “a full menu” of atoms and molecules in the clouds of an exoplanet, and some of them interact. This latest discovery proves that astronomers can look into the atmospheres of strange exoplanets and decipher what is happening or being made chemically – and whether these worlds then contain conditions that could potentially harbor life. (On our planet, atmospheric chemistry, responsible for creating an insulating atmosphere and the protective ozone layer, is vital to life.)
The light from a star can often trigger chemical reactions on a planet, a process called “photochemistry.” This is what happens on WASP-39 b.
“Planets are sculpted and transformed by orbiting in the host star’s radiation pool,” Natalie Batalha, an astronomer at the University of California, Santa Cruz, who contributed to the new research, said in a statement. “On Earth, those transformations allow life to thrive.” (The five research papers showing the discovery are listed in this press release from UC Santa Cruz.)
What the giant James Webb telescope will see Hubble can’t
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Specifically, the Webb telescope found, among other things, the presence of water vapor, sulfur dioxide, carbon monoxide, sodium and potassium. To detect such molecules on distant planets, astronomers are focusing the observatory on known exoplanets in our Milky Way galaxy. Then, as Mashable explained earlier, they do something very clever:
They will wait for planets to travel in front of their bright stars. This starlight travels through the exoplanet’s atmosphere, then through space, and finally into instruments called spectrographs aboard Webb (a strategy called “transit spectroscopy”). They are essentially hi-tech prisms, separating light into a rainbow of colors. Here’s the big trick: Certain molecules, such as water, in the atmosphere absorb specific types or colors of light. “Each molecule has a specific diet,” explains Néstor Espinoza, an exoplanet researcher at the Space Telescope Science Institute, who studies the James Webb Space Telescope.
So if that color is not in the color spectrum observed by a Webb spectrograph, it means it was absorbed by (or “consumed” by) the exoplanet’s atmosphere. In other words, that element is present in the air of that planet. The spectrograph produces lines (indicating different types of light), not pretty pictures; but it is a wealth of valuable information.
The particularly tantalizing detection on WASP-39 b is sulfur dioxide, which is created when light from a star hits a planet’s atmosphere. Using computers, the researchers simulated conditions in this distant atmosphere and determined that photochemistry formed this molecule in the thick, fuzzy clouds of WASP-39 b.
A graphical representation of chemical reactions in the atmosphere of WASP-39 b.
Credit: NASA/JPL-Caltech/Robert Hurt; Center for Astrophysics – Harvard & Smithsonian / Melissa Weiss
“On Earth, those transformations allow life to thrive.”
Now astronomers know they can use Webb to track dynamic atmospheres on other distant worlds in space.
“We will be able to see the big picture of exoplanet atmospheres,” Laura Flagg, an exoplanet researcher at Cornell University who worked on this study, said in a statement. “It’s incredibly exciting to know that everything is going to be rewritten. That’s one of the best parts of being a scientist.”
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An artist’s illustration of molecules reacting to sunlight in the clouds of an exoplanet.
Credit: Melissa Weiss/Center for Astrophysics | Harvard & Smithsonian
Stay tuned. The Webb telescope peers into the atmospheres of the vastly intriguing Trappist planets, seven rocky worlds that exist in the zone of a solar system that is neither too hot nor too cold. Water may slosh across the surface on some of these spheres.