from the still-less-vapor-than-the-phantom-console dept.
To analyze the atmosphere surrounding Tau Boötis b, scientists looked at its faint glow. Different types of molecules emit different wavelengths of light, resulting in signatures known as spectra that reveal their chemical identity.
Scientists have used spectrographic analyses to find water signatures on other alien planets before, but only when those worlds passed in front of their parent stars. Tau Boötis b does not transit in front of its parent star from our viewpoint on Earth, but Lockwood and colleagues were able to tease out the weak light emitted by the planet using the Near Infrared Echelle Spectrograph (NIRSPEC) at the Keck Observatory in Hawaii."