What Webb Telescope Photos Reveal About Atmospheres of Other Planets

While the James Webb Space Telescope woos the world with its clear images of unfathomably distant galaxies and nebulae, it has also showcased its ability to detect atmospheric gases on other planets and play a key part in the search for life elsewhere in the universe.

On Tuesday, NASA released a suite of images taken by Webb, representing its first publicly-available proper cosmic snapshots since it was launched back in December. The photos included an image of the distant galaxy cluster SMACS 0723, which is the deepest and sharpest infrared image of the distant universe ever taken, as well as shots of the Southern Ring Nebula, the Carina Nebula, and the Stephan's Quintet galaxy group.

But the dataset also included information about WASP-96 b, a planet that orbits a sun-like star roughly 1,150 light-years away in the constellation Phoenix. Planets that exist outside of the solar system are called exoplanets.

In a single observation, scientists used Webb to peer at the distant world and study the starlight that shone through its atmosphere as it orbited its nearest star.

James Webb Space Telescope
Using a technique called transit spectroscopy, scientists can work out what the atmospheres of distant worlds are made of. In this combination image, NASA’s James Webb Space Telescope reveals emerging stellar nurseries and individual stars in the Carina Nebula that were previously obscured and the James Webb Space Telescope (Inset). Getty/Nasa/WebbTelescope

In a technique known as transit spectroscopy, this light enters special detectors aboard Webb and is then split into a rainbow of colors. Next, scientists study how some of these colors are blocked or filtered by whatever the light has passed through since certain gasses block certain colors. This data is presented in peaks and troughs on a graph that scientists can read.

In other words, transit spectroscopy allows scientists to study what other planets' atmospheres are made of. It can also reveal temperatures—hotter temperatures tend to cause higher peaks—and other characteristics like the presence of clouds.

Webb is not the only telescope that can do this—Hubble has done it for years—but it is expected to enable more detailed profiles of exoplanets than before. In fact, Webb's infrared exoplanet transmission spectrum collected from WASP-96 b is the most detailed of its kind.

Hubble Space Telescope
Hubble Space Telescope. In this combination image, a 1990 photograph shows the Hubble Space Telescope being deployed from the space shuttle Discovery on mission STS-31. The IMAX Cargo Bay Camera mounted in the payload bay and remotely controlled by the crew members in the cabin and the magnificent spiral galaxy NGC 2276 looks a bit lopsided in this Hubble Space Telescope snapshot. A bright hub of older yellowish stars normally lies directly in the center of most spiral galaxies. But the bulge in NGC 2276 looks offset to the upper left. Nasa/IMAX Cargo Bay Camera /Hubble

The data tantalizingly suggests the presence of water vapor, which scientists are particularly interested in as water is crucial for sustaining life as we know it.

WASP-96 b transit spectroscopy data
This image shows James Webb Space Telescope spectroscopy data for the exoplanet WASP-96 b. The data suggests the gas giant clocks in at 1,350 degrees Fahrenheit. NASA/ESA/CSA/STScl

"The labeled peaks in the spectrum indicate the presence of water vapor," reads a press release from the Webb team. "The height of the water peaks, which is less than expected based on previous observations, is evidence for the presence of clouds that suppress the water vapor features. The gradual downward slope of the left side of the spectrum (shorter wavelengths) is indicative of possible haze."

Don't get excited about life on WASP-96 b, though. The data also suggests a searing atmospheric temperature of 1,350 degrees Fahrenheit. Plus, it's a gas giant, meaning it's probably not as likely to host life as we know it as a rocky planet.

The data might not be as easy on the eyes as the stunning galaxies and nebulae that make up the rest of the first Webb releases—it's important to note that Webb has not taken a direct image of WASP-96 b—but is nonetheless an important finding.

"So yes, you can do science with the pretty pictures, but often it's the spectra that really let us tell the story," wrote Harvard astronomer Jonathan McDowell in a series of tweets on Tuesday.

NASA’s Webb Telescope
This side-by-side comparison shows observations of the Southern Ring Nebula in near-infrared light, at left, and mid-infrared light, at right, from NASA’s Webb Telescope (Inset). This scene was created by a white dwarf star – the remains of a star like our Sun after it shed its outer layers and stopped burning fuel though nuclear fusion. Those outer layers now form the ejected shells all along this view. Nasa/WebbTelescope

A NASA press release stated that the WASP-96 b data "demonstrates that Webb has the power to characterize the atmospheres of exoplanets—including those of potentially habitable planets—in exquisite detail."