When researchers analyzed the curves and compared them with the original images, they figured out which parameters of the curves corresponded to land and cloud cover in the images. Once they knew those relationships, they picked out the parameter most closely related to land area, adjusted it for the 24-hour rotation of the Earth, and constructed the above contour map, soon to be published in The Astrophysical Journal Letters.

The black lines, which mark the median values for the land parameter, serves as an approximate coastline. Rough outlines of Africa (center), Asia (upper right), and the Americas (left) are clearly visible. While this is obviously no substitute for an actual image of an alien world, it may allow future astronomers to assess whether an exoplanet has oceans, clouds, and icecaps—key requirements for a habitable world.