All images: NASA (Artist's concept)
Astronomers for years have been looking for a planet that has similar characteristics to Earth. Several exoplanets have been discovered which might be habitable in future. Here's a look at five such exoplanets.
Located about 2,700 light-years from Earth, Kepler-69c is 70 per cent larger than our planet. According to NASA, astronomers are uncertain about the composition of this exoplanet, but its orbit of 242 days around a sun-like star resembles that of Venus. Kepler-69c's host star is about 80 per cent as luminous as the Sun, which means the exoplanet appears to be in the habitable zone.
Gliese 667 Cc, also referred to as GJ 667 C c, is a super Earth exoplanet that orbits an M-type star. Its discovery was announced in 2013. Its mass is 3.8 Earths, and takes 28.1 days to complete one orbit of its star.
Proxima Centauri b is the closest known exoplanet to Earth- at four light-years. Its mass is 1.07 Earths, it takes 11.2 days to complete one orbit of its star. Although Proxima Centauri b can be found in the habitable zone of its star, the exoplanet is exposed to extreme ultraviolet (UV) radiation.
Kepler-62F is a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. NASA has said that Kepler-62F orbits its host star every 267 days and is roughly 40 per cent larger than Earth in size.
Kepler-452b is the first near-Earth-size planet that orbits around a star the size of the Sun. The size of the orbit of Kepler-452b is nearly the same as that of the Earth at 1.05 AU. Kepler-452b orbits its star once every 385 days.