The word ‘Exoplanet’ seems very fascinating but it simply indicates a planet that is not a part of the solar system to which earth is. Earth-like exoplanets are something to which astronomers continuously look for as it is very much likely to exist in life in the other half of the universe. Earth has a specific mass, size, and livable climate which makes it good for life, and researchers keep an eye on these aspects while looking for earth-like exoplanets. Milky way galaxies possibly have many siblings Earths, as studies in the past suggest that for every five Sun-like stars, one Earth-like planet exists. Earth is special in its own way but there can be countless more like it.
Here are mentioned Exoplanets that are quite similar to Earth.
Kepler-452b – Earth 2.O
Kepler-452b is the closest and one of the earth-like exoplanets discovered so far. It orbits its star at a distance of 1.04 Astronomical units which is nearly the same for the earth to the sun. The time period of the orbit is around 384 days, mass is 1.6 times that of Earth, and has a radius near 1.5 times that of Earth. The Kepler space telescope figured out this exoplanet and NASA announced its discovery on 23 July 2015. It is nearly 1,400 light-years away from the Solar System and around 1,402 light-years away from Earth.
Kepler-452b is the first rocky in Earth-like exoplanets which orbits within the habitable zone of a star quite similar to the Sun. But it is not known yet whether it is completely safe for life because findings showed that it receives little more energy than Earth and thus is more prone to a runaway greenhouse effect.
The next on the list is Kepler-186f nicknamed “Earth’s cousin” which is 490 light-years away from Earth. It is the first earth-sized planet in the habitable zone of its star. It is only 10% bigger than earth. Astronomer Geoff Marcy from the University of California said, “This is a landmark discovery of the first earth-sized planet and results are surely solid. It might be less rocky but I bet my house on it”. Scientists discovered this exoplanet in the outer edge of its system and possibly water might freeze. But the large size suggests that it has a thick atmosphere that insulates it, astronomers added.
It is part of five exoplanets in the Kepler-186 star system. It takes 130 days to orbit its red dwarf star and orbit at a distance of about 32.5 million miles.
NASA officials told that the other four are named Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e and took 4, 7, 13, and 12 days respectively to orbit the red dwarf star in the system respectively and thus very much vulnerable for life. As Kepler-186f is on the outer edge, it is more liveable than its companions.
Astronomers still have not explored this exoplanet fully because of technological limitations but are quite sure that it is earth-sized and more possible to be on Earth-like exoplanets list.
This earth-like exoplanet is just 22 light-years away from Earth. The size is 4.5 times as compared to earth. Researchers are quite not sure whether it is rocky or not. Gliese 667Cc took nearly 28 days to complete one orbit of its star. But its star is a red dwarf which is much cooler than the sun and thus considered to lie in the habitable zone.
However, Gliese 667Cc was discovered using the European Southern Observatory’s 3.6-meter telescope in Chile and its climate mirrored Earth’s climate but was not stable.
Do Earth-like exoplanets really support life?
In the past decade, our vision of what planets exist around stars other than earth burst out. Number of Exoplanets discovered for now in which many are balls of fire and many are balls of ice. Very few of them seem to support life and the Kepler series is one of such a series of earth-like exoplanets. But the important aspect which cannot be neglected is whether these planets are able to support life for the long run like earth.
Exoplanet’s size, habitable zone, a sun-like star are important points that are nearly covered by mentioned earth-like exoplanets but not COMPLETELY. It might be possible that some type of alien life with better technological development exists there, as we lack incomplete exploration of these exoplanets due to lack of technology. Earth is completely stable for now in all aspects and assumed to remain for a long run but such a case might not happen with those exoplanets that mirrored Earth.
Dirk Schulze-Makuch a professor at the Center for Astronomy and Astrophysics at the Technical University Berlin says, “Sometimes it seems difficult to talk about such exoplanets in super habitable zones because we think we are on the best planet. We own complex and many life forms that can survive in extreme environments. It is good to have adaptable life but that doesn’t mean we have the best of everything as there may exist a planet with better living conditions than earth in another corner of the universe.”
It can’t be said fully that we found another earth. As the earth is totally complete in itself for life. But we also can’t ignore the existence of Earth-like exoplanets that support life, as possibly in this big and infinite universe somewhere a planet copying earth resides. The only requirement is technical advancement which may take some time and that’s the other reason for humans looking to make colonies on Mars-like planets.