This image, created by exoplanet researcher Frédéric Pont, uses data from the transmission spectrum of exoplanet HD 209458 b, a.k.a. Osiris, one of the oldest known worlds in the exoplanet pantheon. It's a pretty big planet, about 70 percent the size of Jupiter, and it orbits very close to its sun-like star. As Osiris crosses in front of the face of its star, the starlight passes through its atmosphere. The light can be studied with a spectrograph to determine what the atmosphere contains.