The powerful Webb telescope found water in this alien planet's clouds

Some of the most astonishing discoveries made by the powerful Webb telescope won't come from pretty pictures.

Instead, the instrument can detect what the atmospheres of extremely distant exoplanets, or planets beyond our solar system, are composed of. On Tuesday, NASA revealed that the James Webb Space Telescope had detected the "distinct signature of water" on a hazy exoplanet 1,150 light-years away.

It's not the first detection of water molecules on another world. But the Webb telescope — built with a 21-foot mirror more than two-and-a-half times larger than Hubble's — allows unprecedented views into these distant planets.

"While the Hubble Space Telescope has analyzed numerous exoplanet atmospheres over the past two decades, capturing the first clear detection of water in 2013, Webb’s immediate and more detailed observation marks a giant leap forward in the quest to characterize potentially habitable planets beyond Earth," the space agency said.

The Webb telescope is spending considerable time — a whopping 25 percent of its first year — peering into the skies of exoplanets. This particular world, dubbed WASP-96 b, is nothing like Earth. It's a type of planet called a "hot Jupiter" that doesn't exist in our solar system. WASP-96 b is a world a little larger (though less massive) than our gas giant Jupiter that zips extremely close around its sun-like star. Temperatures are hotter than a pizza oven, exceeding 1,000 degrees Fahrenheit.

To detect molecules — like water, methane, and carbon dioxide — on distant planets, astronomers point the telescope at known exoplanets in our Milky Way galaxy. Then, as Mashable previously explained, they do something very profoundly clever:

They'll wait for planets to travel in front of their bright stars. This starlight passes through the exoplanet's atmosphere, then through space, and ultimately into instruments called spectrographs aboard Webb (a strategy called "transit spectroscopy"). They're essentially hi-tech prisms, which separate the light into a rainbow of colors. Here's the big trick: Certain molecules, like water, in the atmosphere absorb specific types, or colors, of light. "Each molecule has a specific diet," explained Néstor Espinoza, an exoplanet researcher at the Space Telescope Science Institute, which runs the James Webb Space Telescope.

So if that color doesn't show up in the spectrum of colors observed by a Webb spectrograph, that means it got absorbed by (or "consumed" by) the exoplanet's atmosphere. In other words, that element is present in that planet's skies. The spectrograph produces lines (designating different types of light), not pretty pictures; but it's a wealth of invaluable information.

The spectrum of light recently captured by Webb (below) shows that WASP-96 b blocked light waves from water molecules — meaning there are water molecules present in its thick, fluffy clouds.

The atmospheric composition of WASP-96 b, which indicates the presence of water. Credit: NASA / ESA / CSA / STScI

Tweet may have been deleted (opens in a new tab)

The Webb telescope's Near-Infrared Imager and Slitless Spectrograph, or NIRISS, captured this detailed data while peering at WASP-96 b for just over six hours. Planetary scientists are excited about what else they'll find on other distant worlds. "This NIRISS observation demonstrates that Webb has the power to characterize the atmospheres of exoplanets — including those of potentially habitable planets — in exquisite detail," NASA said.

Webb's scientists plan to also point the powerful telescope at smaller, rocky, perhaps Earth-like worlds. There could be well over a trillion exoplanets in our galaxy alone. But we know vanishingly little about them.

"We've only been able to barely scratch the surface," the Space Telescope Science Institute's Espinoza told Mashable.