When we consider the vastness of the universe, it can be quite difficult to believe we are the only intelligent beings out there. Our galaxy alone is home to over 200 billion stars, nearly all of them orbited by planets we are still yet to discover.
Considering there are at least 100 billion galaxies in the observed universe, let alone the galaxies we have not observed yet, we can assume that there are trillions upon trillions of planets just waiting to be explored.
Yet with the technology available to us today, scientists and astronomers have only been able to find a handful of planets they think may host alien life. Here’s a look at nine of them.
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Kepler-22b is an exoplanet found within the habitable zone of Kepler-22, a Sun-like star in the Cygnus constellation, located about 600 light-years from Earth.
NASA describes Kepler-22b as a “super-Earth” at 2.4 times Earth’s radius that could be covered in a “superocean” and potentially gaseous.
NASA’s website says that based on recent computer modelling, the ocean world tipped on its side could be “comfortably habitable” and that average temperatures on the exoplanet are approximately 15.5 degrees Celsius.
It adds: “Because of its radical tilt, its north and south poles would be alternately bathed in sunlight and darkness, for half a year each, as the planet circled its star.”
Trappist-1e was discovered orbiting the ultra cool dwarf star Trappist-1 in 2017. It is located approximately 40 light-years from Earth in the constellation of Aquarius.
The terrestrial exoplanet’s mass is 0.692 that of Earth’s and is believed to have a compact atmosphere like the terrestrial planets in our solar system.
According to the Habitable Exoplanets Catalog, the possibly ocean-hosting planet which takes 6.1 days to complete one orbit of its star, is one of the most potentially habitable exoplanets discovered so far.
All of these planets were discovered in 2013 in the Gliese 667 system. Gliese 667 is actually a triple-star system in the Scorpius constellation about 22 light-years from Earth, meaning these planets actually have three suns.
With all three of these planets found inside the habitable zone of their star(s), they could all potentially host water and life itself. These planets are tidally locked so only one side faces their star(s) while the other side remains in darkness.
Gliese 667Cc has a radius 1.8 times that of Earth and takes 28 days to complete an orbit, while Gliese 667Ce and Gliese 667Cf both have a radius 1.5 times that of Earth’s. It takes Gliese 667Ce 62 days to complete an orbit, and Gliese 667Cf 39 days.
Proxima Centauri b is the closest exoplanet to Earth and is potentially habitable. Found in 2016 orbiting in the habitable zone of the red dwarf star Proxima Centauri, the closest star to our Sun approximately 4.2 light years away, Proxima Centauri b’s mass is 1.27 the Earth’s and it takes 11.2 days to complete one orbit of its star.
It is not known at this time if the planet has an atmosphere and it is not believed that the planet could provide a stable orbit to host any moons. Although the planet could potentially hold water, being tidally locked around its star means that perhaps only part of the planet could be habitable.
Discovered in 2019 orbiting within the habitable zone of Teegarden's Star, an M-type red dwarf around 12 light years away from our Solar System, this exoplanet has a mass that is 1.05 that of Earth’s.
Teegarden’s Star b takes 4.9 days to complete one orbit of its star and is believed to be a rocky planet with a chance it could host oceans of water. The planet is tidally locked, but under the right conditions the planet’s twilight strip may very well be hospitable to life.
TOI-700 d is another “super Earth” exoplanet with a mass 1.57 times our own planet. Orbiting the red dwarf TOI 700 in the constellation of Dorado once every 37.4 days, it is located roughly 101.4 light-years from Earth.
The exoplanet, which was discovered in 2020, is estimated to receive about 8 percent the energy that the Earth receives from the Sun and could have an average temperature of −4.3 degrees Celsius if it indeed has an Earth-like atmosphere.
LHS 1140 b has a mass that is 6.38 times that of Earth’s and takes 24.7 days to complete one orbit of its star, the red dwarf LHS 1140, 40 light years away.
Discovered in 2017, LHS 1140 b is considered to be one of the densest planets ever found, with a density more than twice that of Earth and a high surface gravity of about 2.41 Earth's.
The planet’s average surface temperature is believed to be around −7 degrees Celsius, with a huge possibility that it could host water and a hydrogen-dominated atmosphere. A year on LHS 1140 b is about 24.7 days.
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