In a dim and faraway solar system, astronomers have for the
first time discovered a rocky, Earth-sized planet that might hold liquid
water—a necessary ingredient for life as we know it.
The planet Kepler-186f is the fifth and outermost world
orbiting the red dwarf Kepler-186. The slow-burning sun is smaller and cooler
than our own. Too faint to be seen without a telescope, it's roughly 500 light
years away in the direction of the northern constellation Cygnus (a light year
is the distance light travels in a year).