As of mid-2016, we have confirmed the existence of over 3,200 planets outside of our solar system. The majority of these exoplanets were discovered by the Kepler Space Telescope which scans only 1/400 of the sky. The number of potentially habitable worlds in our galaxy alone is vast. Within our lives, we will likely see the first human set foot on another planet, Mars. Once our species masters the technology needed for interstellar space travel, our descendants will see the first human set foot on another planet, light-years away, orbiting another star.
The planets below are ranked by the Earth Similarity Index (ESI). An ESI of 0.0 means the world is an uninhabitable gas giant. Mars has an ESI of 0.7 and a planet rating 1.0 would be almost an exact copy of Earth.
