Is there life out there? This question has captured human curiosity for centuries. In an attempt to answer this question, NASA launched its space observatory Kepler in 2009 to search for Earth-like planets orbiting in habitable zones of other stars.
The recent “tip-of-the-iceberg discovery” of Kepler-186 f inspired us to look back at 5 Earth-like planets which are potentially hospitable to life, starting from the one under discussion.
Being the first planet with a radius similar to Earth's, Kepler-186f is being called the “most Earth-like planet yet”. The rocky planet has the potential to hold water in liquid form, which is critical for the existence of life. Its distance from Earth is around 490 light years.
In the words of UC Berkeley astronomer Geoffrey Marcy, "this is the best case for a habitable planet yet found. The results are absolutely rock solid."
Kepler-22b was discovered in 2011. Located 600 light years away from Earth, it was the first known transiting planet to orbit within the habitable zone of a Sun-like star.
Physically, Kepler-22b can be described as “ocean like”. While speculating on the possibility of life on the planet, Kepler mission scientist Natalie Batalha said, “if it is mostly ocean with a small rocky core, it's not beyond the realm of possibility that life could exist in such an ocean.”
Located about 1,200 light years from Earth in the constellation of Lyra, Kepler-62e is 60 percent larger than Earth. It is one of the two Earth-like and potentially inhabitable planets around the star Kepler-62.
It has a rocky composition with probably a substantial amount of water.
Neighboring the previously discussed Kepler-62e in the constellation of Lyra, Kepler-62f was described by Dimitar Sasselov of Harvard University as “cooler, but still potentially life-friendly”
While discussing the possibility on life on both these planets, Kepler science principal investigator Bill Borucki, who led the team that discovered Kepler-62e and Kepler-62f said, "Look at our own ocean — it is just absolutely full of life. We think, in fact, life [on Earth] might have begun there."
Gliese 667 Cc
The discovery of Gliese 667 Cc was made public in by the European Southern Observatory's HARPS group. It is said to be 85 percent similar to Earth.
It is located in a triple star system (Gliese 667) in the constellation Scorpius, 22.7 light years away from Earth.