For the first time, researchers have found a planet outside of our solar system that has water on it.
Located just a short 110 light-year trip from Earth — for context, Mars is just eight light minutes away from us — K2-18b represents a breakthrough discovery as scientists sift through thousands of exoplanets in search of signs of life. According to astronomers and researchers involved in the project, K2-18b is the only known planet outside of our solar system that has the proper temperature and atmosphere to support life. The determination that water vapor is present on the rocky exoplanet suggests that it is the “best candidate for habitability.” What isn’t known, though, is whether K2-18b has surface water like oceans or lakes. It also isn’t clear whether or not it currently hosts any life forms.
While K2-18b represents a potential to be Earth-like, it also is quite different from the planet that we call home. Scientists say that it is about twice the size of Earth and about eight times as massive. Its atmosphere contains a much higher concentration of hydrogen gas than ours, which is largely dominated by nitrogen. K2-18b is said to have about the same density as Mars, suggesting that it is a rocky planet. That’s a good sign for the possibility of the exoplanet being habitable.
Prior to the discovery of K2-18b, the search for an inhabitable planet outside our solar system was feeling a bit futile. Scientists have spent a considerable amount of time trying to track down planets with traces of water in the atmosphere and have come up largely empty. There have been instances of water found on gassy exoplanets, but those are not believed to be habitable by human-like life forms because they show limited capacity for carbon, nitrogen and oxygen — the building blocks for life as we know it. The goal for discovery has always been to find a rocky exoplanet with water, and after studying thousands of possible destinations, K2-18b finally represents a possibility for supporting life.