How do you understand something you can barely see, never visited and is light years away from us? By being really, really smart at connecting dots. In this video, NASA explains its process in figuring out what alien planets are like with the limited information it has.
It's like being able to create a clear picture just from describing the scene. Well, if that scene description was light years beyond us, of course. NASA writes about how it is able to determine an exoplanet's size, composition and atmospheric make up:
By observing periodic variations in the parent star's brightness and color, astronomers can indirectly determine an exoplanet's distance from its star, its size, and its mass. But to truly understand an exoplanet astronomers must study its atmosphere, and they do so by splitting apart the parent star's light during a planetary transit
It's pretty incredible how NASA can figure that all out with just a few basic concepts.