Kepler-186f's surface features are also a mystery. "We only know that it is at the right distance [from its star] to allow the existence of water in liquid form," Quintana said.

Kepler-186f may be close to Earth size, but it’s hardly close by. It sits some 490 light-years away in the constellation Cygnus, and circles its home star, Kepler-186, in just 130 days ...

With its smaller size, Kepler 186f is more likely to have an Earth-like rocky surface, another step in astronomers’ quest for what might be called Earth 2.0. Advertisement ...

Artist's concept of Kepler-186f Scientists using NASA’s Kepler telescope have found the first Earth-size planet orbiting its star at just the right distance for water to exist on its surface.

Kepler-186f orbits at 32.5 million miles (52.4 million kilometers) from its parent star. Its year is 130 Earth days. Earth-Size Planet Kepler-186f, a Possibly Habitable Alien World (Gallery) ...

Kepler-186f is about 11 percent larger than Earth in diameter, which means it has nearly 25% more surface area. Kepler-186f is more like our bigger sister than our twin.

Kepler-186f seems to orbit the outer edge of its habitable zone. However, being slightly larger than the Earth means it is likely to have a thick insulating atmosphere that would stop its surface ...

That is about all that we know about 186f for now. Kepler doesn’t have the capacity to give information about the planet’s atmosphere, its surface temperature, or even its density.

So far, Kepler-186f appears almost to be a Goldilocks — not too big, not too far from its star, maybe just right. The planet has a shorter year than we do, orbiting its star once every 130 days.

Kepler-186f, meanwhile, fits the description of a rocky planet with a benign atmosphere that lies within the water-friendly “Goldilocks zone” which is neither too hot, nor too cold for life.

"Third, red dwarf stars, like the parent (of Kepler-186f) are by far the most abundant stars in our galaxy, making up about 80 percent of the nearest stars to the Earth.

Kepler-186f is about 11 percent larger than Earth in diameter, which means it has nearly 25% more surface area. Kepler-186f is more like our bigger sister than our twin.