One Transit, One Year
For ten hours, the star HD 137010 dimmed a little, like a lamp with a speck of dust on it. The K2 telescope caught this in 2017, and in all the observing time, it happened only once. Astronomers realized: a planet had passed in front of the star.
This way of finding worlds is called the transit method. When a planet crosses the star's disk, the star briefly fades.