How does the James Webb Space Telescope discover exoplanet atmospheres?

The James Webb Space Telescope helps us see what’s in the air around faraway planets, like how we can tell if a friend is holding up a red balloon or a blue one from across the room.

Imagine you're at a party with your friend behind a curtain. When they speak, their voice changes slightly depending on what's in front of them, maybe a soft cloth or a loud fan. By listening closely to how their voice sounds different each time, you can guess what’s in front of them without seeing it.

That’s kind of like how the James Webb Space Telescope works when it studies exoplanet atmospheres. When an exoplanet passes in front of its star, some of the star's light goes through the planet’s atmosphere on its way to us. Different gases in that atmosphere change the color or brightness of the light we see.

By comparing the light before and after the planet passes by, like listening for changes in your friend's voice, scientists can figure out what gases are floating in the air around the exoplanet, just like you might guess if your friend is holding up a red balloon or a blue one.