Kepler-186 f is often called the “first Earth-sized habitable zone world”—discovered in 2014 by NASA’s Kepler telescope. It’s about 1.2 times Earth’s size and orbits a cool red dwarf star every 130 days, receiving just enough light to possibly have liquid water.
On the outer edge of the habitable zone, it might be rocky with oceans or ice caps if it has a thick atmosphere to trap heat. The red dwarf star would paint the sky in dramatic reds—like eternal sunset. No direct images yet, but it’s a top target for future studies hunting biosignatures.
This planet proved Earth-like worlds exist around other stars—and kicked off the search for true alien Earths.