The new discovery of an Earth-like exoplanet around Proxima Centauri, the nearest star of the Earth, means that potential life-bearing planets are right in our backyard. Now’s the time to take stock of all the exoplanets we’ve so far, and determine which of them are “super-habitable”- practically Earth’s splitting image. Here’s a look at the most promising real estate in the galaxy as of late summer 2016.
1. Proxima b
1.3 times the Earth’s mass.
4.23 light-years away.
The newly discovered the Proxima b is not only the nearest exoplanet to the Earth, but is the nearest potentially habitable exoplanet as well. It’s rocky planet in a close, 11-day orbit-which makes it warm enough for liquid water to exist on it’s surface. Proxima will certainly be the prime target for the first wave of interstellar probes.
2. Kapteyn b
4.8 times the Earth’s mass
12.8 light-years away.
At over 11 billion years old, Kapteyn b may be the oldest potentially habitable exoplanet known. If life has evolved on Kapteyn b, it’s likely to be over twice the age of life on Earth.
3. Wolf 1061 c
4.3 times the Earth’s mass.
13.8 light-years away.
Wolf 1061 c is one of three planets in orbit around a red dwarf, and is one of the nearest potentially habitable exoplanets. With one face permanently turned to its star, and of surface gravity 1.6 times the Earth’s, any life here is likely to be very strange indeed.
4. Gliese 667 c system
22 light-years away.
The Gliese 667 c system consists of at least one, and possibly three, “super-Earth” planets in the star’s habitable zone (HZ).
If any photosynthetic life exists on the planets of Gliese 667 c, It’s likely to be a deep black in colour in order to absorb the predominantly infrared radiation of its primary.
39.5 Light-years away.
TRAPPIST-1 is an “ultracool” dwarf star, scarcely larger than Jupiter and with only 0.05% of the Sun’s luminosity.
The TRAPPIST-1 system consists of three rocky, Earth-sized planets. The two innermost planets are likely hotter than the Earth but may still have habitable areas; the outermost planet is probably much colder, but could still be habitable.
6. Kepler-186 f
1.5 times the Earth’s mass.
561 light-years away.
Kepler-186 f is part of a 5-planet system around a red dwarf star. It’s considered to be one of the best candidates for possible extrasolar life, and was targeted in 2014 by the Allen Telescope Array as part of the SETI Program.
7. Kepler-1229 b
2.7 times the Earth’s mass.
769 light-years away.
Kepler-1229 b orbits its red dwarf primary with a year similar to Mercury’s (about 86 days). Though probably tidally locked, if it has a dense enough atmosphere, a global greenhouse effect may be sufficient to conduct heat from the sunward to the nightward side.
8. Kepler-442 b
2.3 times the Earth’s mass.
1,115 light-years away.
Orbiting a distant orange dwarf star, Kepler-442 b is considered to be one of the likeliest candidates for habitability yet discovered. With a lifespan of 30 or more billion years for the planet’s star, any life that evolves here can look forward to a lengthy career.
1,200 light-years away.
An orange star somewhat smaller and cooler than the sun, with a 5-planet system-two of which, Kepler-62 e and Kepler-62 f, fall within the star’s habitable zone. Kaplar-62 e may be a “super Earth” terrestrial or ocean world. Kepler-62 f is more distant, and may be covered with ice.