For the past three years, Kepler telescope of NASA found another 4,000 new planets outside of the solar system. Scientists narrowed down the list and found those planets that have liquid water and habitable for alien life.

NASA identified 20 planets that are earth-like out of 216 planets orbiting the habitable zone. However, they said that these planets are too far for them to visit. In an e-mail to Huffington Post, Dr. Stephen Kane of San Francisco State University said, "Considering that the diameter of our galaxy is around 100,000 light years, that's still relatively close." Referred to as Goldilocks Zone, scientists are also calculating the size of these exoplanets and whether or not it is habitable.

The newly discovered planets are considered rocky and these include Kepler-186 f, Kepler 283-c, Kepler-62f and Kepler 296f, according to Daily Mail UK. The classification of these planets as habitable zone depends on the planet's distance from its star. Take for example, the planet Venus that experiences runaway greenhouse has due to its closeness from its star. Another is the planet Mars where the water freezes because it's too far.

Astronomer from other institutions like Dr. Seth Shostak of SETI Institute in Mountain View, California is optimistic of this newly discovery and told Huffington Post, "We know that approximately one in five stars could host a habitable planet. There are tens of billions of these life-friendly worlds in a typical galaxy." He said that they accepted this humbling, astounding and obvious challenge and that means they are up for it.

Meanwhile, what they can do is to focus their efforts on the planets that are possible for yielding evidence of an extraterrestrial life and hope that they could provide as much information whether or not an alien life exists in the newly discovered exoplanets together with the existence of life on earth.