Exoplanet atmospheres

In this activity developed by the Institute of Physics, students use simple diffraction gratings to observe the spectra from different sources, and deduce how scientists can work out which chemicals are present in an exoplanet’s atmosphere. When an exoplanet passes in front of its star, some of the starlight is absorbed by the exoplanet’s atmosphere. Astronomers look for changes in the spectrum of the light from a star. If they observe that some wavelengths become dimmer as the exoplanet transits across in front of it, they can deduce which elements and compounds are present in the planet’s atmosphere.