The discovery is the first successful atmospheric detection for an exoplanet orbiting in its star’s ‘habitable zone’, at a distance where water can exist in liquid form, they said.
“Finding water in a potentially habitable world other than Earth is incredibly exciting,” said first author Angelos Tsiaras from the University College London (UCL) in the UK.
K2-18b, super-Earth planet
K2-18b is one of hundreds of “super-Earths” – exoplanets with masses between those of Earth and Neptune – found by Kepler. NASA’s TESS mission is expected to detect hundreds more super-Earths in the coming years. The next generation of space telescopes, including the James Webb Space Telescope, will be able to characterize exoplanet atmospheres in more detail.
K2-18b, is more hostile than Earth
The researchers noted that given the high level of activity of its red dwarf star, K2-18b may be more hostile than Earth and is likely to be exposed to more radiation.
K2-18b was discovered in 2015 and is one of hundreds of super-Earths planets with a mass between Earth and Neptune — found by NASA’s Kepler spacecraft. “With so many new super-Earths expected to be found over the next couple of decades, it is likely that this is the first discovery of many potentially habitable planets,” said co-author Ingo Waldmann from UCL
Is the Earth unique?
“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?” said Tsiaras.
The team used archive data from 2016 and 2017 captured by the ESA/NASA Hubble Space Telescope and developed open-source algorithms to analyse the starlight filtered through K2-18b’s atmosphere.