Would large amounts of water on the surface provide a glint of light in both the infrared and visible spectrum if we study a distant exoplanet long enough? That’s the premise of an investigation now in progress, one aiming to find Earth-like planets in the habitable zone of a star.

If the goal sounds chimerical now, bear in mind that various planet-hunting missions like Terrestrial Planet Finder (in its various incarnations) and Darwin are being designed to allow direct observation of planets as small as the Earth. Such observatories, which may be in place within two decades or less, could also examine the visible and infrared light curve of such planets over the course of an entire orbit.

According to the paper on this work, half of all detected extrasolar planets will have orbital inclinations that make it possible to detect surface oceans.