NASA's Kepler space telescope has revolutionized our view on the vast number of exoplanets orbit other stars in our galaxy -- but how many are what | NASA

Habitability Index: A New Way to Rank Alien Worlds

With more than 1,000 confirmed planets discovered by the Kepler space telescope alone, deciding which ones are 'habitable' is an overwhelming prospect -- but there could soon be a way.

October 28, 2015
3:50 PM EDT
A diagram of what happens to the light curve of a star when a planet passes in front of it. | NASA Ames
Artist's conception of TESS (Transiting Exoplanet Survey Satellite) and planets passing in front of a star. | MIT/TESS team
In this artist's conception is exoplanet OGLE-2005-BLG-390L b, which has an estimated surface temperature of just 50 Kelvin (-370 degrees Fahrenheit, or -223 degrees Celsius.) | NASA
This diagram of the solar system shows how eccentric the orbits of dwarf planets Pluto and Eris are, compared with the planets. | NASA
The habitability index would rank worlds such as Kepler-62f, a small super-Earth shown in this artist's impression. | NASA/Ames/JPL-Caltech