Call it an astronomical discovery.
For the first time ever, scientists have detected water in a planet outside the solar system with temperatures suitable for life.
University College London announced Wednesday that a team of researchers found water vapor in the atmosphere of K2-18b, an exoplanet located 110 light-years away.
The planet, first identified in 2015, is eight times the mass of Earth and is in a so-called “habitable zone,” the region around a star in which liquid water could potentially surface.
The discovery makes the planet a plausible candidate for alien life, but the scientists cautioned that K2-18b may be “more hostile than Earth” and is likely exposed to more radiation. Its red dwarf star is much smaller, cooler and more active than the sun.
“Finding water in a potentially habitable world other than Earth is incredibly exciting,” lead author Angelos Tsiaras said in a news release. “K2-18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition.
“However,” he said, “it brings us closer to answering the fundamental question: Is the Earth unique?”
For the first time, researchers using Hubble have detected water vapor signatures in the atmosphere of a planet beyond our solar system that resides in the "habitable zone." For more information: https://t.co/vUa2NbkbwU pic.twitter.com/ey3uz2ynMk
His team used archive data captured by the Hubble Space Telescope in 2016 and 2017 to analyze the starlight filtered through K2-18b’s atmosphere. The study revealed the molecular signature of water vapor and suggested the presence of hydrogen and helium in the planet’s atmosphere.
NASA, which leads the Hubble project with the European Space Agency, describes the planet as a “super-Earth,” one of hundreds of exoplanets with masses between those of Earth and Neptune. The U.S. agency expects to detect hundreds more super-Earths in the coming years.
“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,” study co-author Ingo Waldmann wrote in Wednesday’s release. “This is not only because super-Earths like K2-18b are the most common planets in our Galaxy, but also because red dwarfs — stars smaller than our Sun — are the most common stars.”