The 6 Most Earth-like Alien Planets

A picture of Earth and artist's interpretations of several exoplanets that could be like our own. From left: artist's impressions of Kepler-22b, Kepler-69c, Kepler-452b, Kepler-62f and Kepler-186f. A picture of Earth is at far right.

Discovering the first true “alien Earth” is a long-held dream of astronomers—and recent exoplanet discoveries suggest that their dream will come true in the not-too-distant future.

Scientists have found nearly 2,000 alien planetssince the first such world was confirmed orbiting a sunlike star in 1995. More than half of these discoveries were made by NASA’s , which launched in 2009 on a mission to determine how common Earth-like planets are throughout the Milky Way galaxy.

Kepler’s observations have shown that small, rocky worlds like our own are abundant in the galaxy, and some of them may be capable of hosting life as we know it. []

To qualify as potentially life-friendly, a planet must be relatively small (and therefore rocky) and orbit in the “habitable zone” of its star, which is loosely defined as a location where water can exist in liquid form on a world’s surface. When telescope technology improves, other factors will be considered as well, such as the planet’s atmospheric composition and how active its parent star is.

While Earth 2.0 remains elusive, here are what  the closest known analogues to our home planet.

Gliese 667Cc

However, Gliese 667Cc—which was discovered with the European Southern Observatory’s 3.6-meter telescope in Chile—may orbit close enough in to be baked by flares from the red dwarf.

Kepler-22bKepler-22b lies 600 light-years away. It was the first Kepler planet found in the habitable zone of its parent star, but the world is considerably larger than Earth—about 2.4 times our planet’s size. It’s unclear if this “super-Earth” planet is rocky, liquid or gaseous. Its orbit is about 290 days long.

Kepler-69c

The planet completes one orbit every 242 days, making its position within its solar system comparable to that of Venus within ours. However, Kepler-69c’s host star is about 80 percent as luminous as the sun, so the planet appears to be in the habitable zone.

Kepler-62f

The Kepler-62 system lies about 1,200 light-years away.

Kepler-186fKepler-186f receives just one-third of the energy from its star that Earth gets from the sun.

Kepler-186f’s parent star is a red dwarf, so the alien world is not a true Earth twin. The planet lies about 500 light-years from Earth.

Kepler-452bKepler-452b has a “better than even chance” of being rocky, its discoverers have said. Kepler-452b resides 1,400 light-years from Earth.

Earth (for comparison)

SPACE.com

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