NASA astronomer Lucy McFadden and UCLA graduate Carolyn Crow recently made a discovery that will help identify characteristics of extrasolar planets, such as the compositions of their surfaces and atmospheres. By comparing the reflected red, blue, and green light from planets in our solar system, a team led by Crow and McFadden was able to group the planets according to their similarities. As it turns out, the planets fall into very distinct regions on this plot, where the vertical direction indicates the relative amount of blue light, and the horizontal direction the relative amount of red light.
This technique works even when the source of the reflected light is visible only as a point, like exoplanets appear when observed through a telescope. Therefore, scientists can use it to identify earthlike planets more easily.