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A Wet, Warm World
Meet the first exoplanet discovered within the habitable zone of its star with confirmed water in its atmosphere: K2–18b
If water is a requirement for life, have we just found our first best candidate for extraterrestrial habitation?
K2–18b is the second world out from its sun, a red dwarf star, in a solar system 111 light years away from Earth.
It is considered a “super-Earth”, many times our own planet’s mass.
At over 100 light years distant, it would take us, using current space travel technology, a bit over 1,000 years to send a probe there to investigate the planet up close. We would need to wait another 111 years to receive any data back from the probe. A current NASA project is developing a tiny probe that could potentially reach 1/5 lightspeed, cutting our wait time nearly in half.
This new discovery was published in Nature Astronomy.
K2–18b’s atmosphere contains water vapor, and also orbits its star (K2–18) at a distance that allows for liquid water. This means the planet’s average temperature might be moderate enough to allow complex life forms to evolve.
Angelos Tsiaras, of University College London’s Centre for Space Exochemistry Data, and one of the researchers behind the discovery using the Hubble Space Telescope, has more to say:
Finding water in a potentially habitable world other than Earth is incredibly exciting. K2–18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to answering the fundamental question: Is the Earth unique?
The atmosphere also shows sign of helium and hydrogen, and may also contain significant amount of nitrogen and methane. However, oxygen presence seems severely limited.
With a 33 day orbit around a cool M3 dwarf, K2–18b receives virtually the same amount of total radiation from its host star (1441±80 W/m2) as…
