Finding Water Vapor on an Exoplanet

One of the greatest discoveries about an exoplanet was the recent confirmation of water vapor on HAT-P-11b. This discovery is the result of combined observations from three different space telescopes. The data from these observations are processed using transmission spectroscopy, which you might be familiar with in an intro physics or chemistry class: The energy levels of a given compound permit the transmission of only specific wavelengths of light; by examining the wavelengths that transmit through a material, we can determine what the material is made of.