A mere 500 light years away:

A new planet that scientists are calling a close “cousin” of Earth was discovered nearly 500 light years away in the constellation Cygnus, NASA scientists announcedThursday. Called Kepler-186f, the exoplanet – a term given to any planet outside our solar system – is about the same size as Earth and is just the right distance from its host star for liquid water.

NASA says of all the exoplanets Kepler has spotted since it was launched in 2009, Kepler-186f is the closest thing yet to a planet that could possibly support extraterrestrial life.

"This is an historic discovery—the first Earth-size planet found in the habitable zone around its star," Geoff Marcy of the University of California, Berkeley, a planet hunter who was not involved with the team that made the discovery, told National Geographic.  "This is the best case for a habitable planet yet found."

The discovery is detailed in a new study in the journal Science.

“The quest for Earth-like planets is a major focus of current exoplanet research,” the authors note. “Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces.”

Scientists say Kepler-186f is likely to be rocky and orbits its star once every 130 days. Its star is a red dwarf star called an M dwarf that is only about half as large as the sun, and correspondingly cooler and dimmer. According to DNA India, the brightness of the star on Kepler-186 at high noon is only about as bright as our sun looks to us about an hour before sunset.

Marcy said the surface temperature on the planet is “likely cool, similar to dawn or dusk on a spring day.”