Thrilled scientists used Webb telescope to find rocky, Earth-size planet

 

But it's also equipped with special instruments, called spectrographs, that can detect what's in an exoplanet's skies. 

Astronomers 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 the Webb telescope (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. 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.

There isn't another operational telescope around today that can sleuth out what lies in the atmosphere of an Earth-sized planet. Earth is relatively small. That's why Jupiter-like exoplanets are easier to detect and analyze.

A graphic showing how the James Webb Space Telescope's spectrograph looked into LHS 475 b's atmosphere. Credit: Credit: Illustration: NASA / ESA / CSA / L. Hustak (STScI); Science: K. Stevenson / J. Lustig-Yaeger / E. May (Johns Hopkins University Applied Physics Laboratory) / G. Fu (Johns Hopkins University) / S. Moran (University Of Arizona)

It's likely that Webb will detect and analyze other Earth-sized, rocky worlds. "These first observational results from an Earth-size, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb," NASA's Clampin said.