For the first time in history, water vapor has been found on a planet outside of our solar system. The exoplanet called K2-18b orbits a small red dwarf star about 110 light-years away from us, in the constellation Leo. What is most intriguing is that the planet sits in the so-called habitable zone, which means that it is neither too close, nor too far away from its star, so the temperature could be just right for liquid water to exist down there. We all know that liquid water is one of the key ingredients for the existence of life as we know it (excitement building!).
K2-18b has a mass eight times greater than Earth’s and it is bigger in size at about 2.7 times the radius. That means that the gravity on the surface of the planet would be much higher than on our planet.
Besides revealing the molecular signature of water vapor, scientists also found evidence of hydrogen and helium in the planet’s atmosphere. However, further research and analysis need to be done in order to determine how exactly does K2-18b look like and what is the atmosphere consisted of. Liquid water would only be possible if the planet turns out to be terrestrial in nature, and not gassy like Neptune. Clouds filled with water could cover the “whitish” planet.
K2-18b is much closer to its star than our planet is to the sun, and it completes an orbit in just 33 days. Because of the high level of activity of its red dwarf star, the exoplanet is probably a bit more hostile to life as we know it on Earth, as it is likely to be exposed to more high-energy radiation.