Astronomers have known for some time that water is quite abundant in the universe. But so far, water found on other planets, moons, and asteroids has shown up in its solid form: ice. Now, a team of scientists from the Institute for Research on Exoplanets at the Université de Montréal has confirmed for the first time ever that water vapor exists on another planet, Futurism reports.
“This represents the biggest step yet taken towards our ultimate goal of finding life on other planets, of proving that we are not alone,” lead author and professor at the Université de Montréal Björn Benneke said in a statement. “Thanks to our observations and our climate model of this planet, we have shown that its water vapour can condense into liquid water. This is a first.”
Since its launch in 2009, the Kepler mission has discovered two-thirds of all known exoplanets. Many exoplanets are gas giants like Jupiter, but some are rocky like Earth. Data from the intrepid planet-finding spacecraft has shown that five to 20 percent of these Earth-like planets orbit in the so-called Goldilocks zone of their star.
It’s one thing to know that these Earth analogs orbit in the habitable zone. However, detecting the composition of their atmospheres has proven difficult. That is until Benneke and his team took a closer look at a planet called K2-18b.
The exoplanet measures in at about nine times the mass of Earth. It orbits an M-type star 111 light-years away at about the same distance that the Earth orbits the Sun. K2-18b also receives about the same amount of energy from its star.
K2-18b is no stranger to Benneke. The professor and his team discovered the planet back in 2016 using the Spitzer Space Telescope. Its similarities to Earth prompted Benneke and his team to keep a close eye on the exoplanet.
By observing the planet’s path in front of its star eight times using the Hubble Space Telescope, the team was able to discern that it is enveloped in a gaseous atmosphere containing water vapor. This bodes well for the possibility that it condenses and rains liquid water onto K2-18b’s surface.
Signs of Life?
Interestingly, scientists believe that the atmosphere might be too thick for life to evolve on the surface. The intense pressure of the heavy atmosphere would simply be too much to overcome. Still, discovering the first signs of water somewhere other than Earth in a form that’s not ice is a big deal. It means that astronomers now have the tools to actually “see” whether a planet has a watery atmosphere or not.
Just as Kepler revolutionized the discovery of exoplanets, the technique Benneke and his team used to find water vapor could revolutionize the way that astronomers look for life beyond Earth. It’s likely only a matter of time before one of these watery worlds gives up the signs of life.