K2-18 b is one of the most studied and mysterious exoplanets known to modern science, located approximately 124 light-years from Earth in the constellation Leo. It orbits a cool red dwarf star, K2-18, and completes a full orbit in just 32.9 Earth days. Despite such a short year, the planet lies in its star's habitable zone — a region where temperatures, under certain conditions, allow liquid water to exist. K2-18 b is significantly larger than Earth: its radius is approximately 2.4 times that of Earth, and its mass is almost 9 times greater, placing it among the super-Earths or sub-Neptunes. Due to its high mass, surface gravity, if it exists at all, would be significantly stronger than Earth's. Scientists speculate that this planet may represent an entirely different type of world, unlike either Earth or the gas giants of the Solar System. According to one of the most popular hypotheses, K2-18 b may be a so-called "Hycean World" — a planet covered by a gigantic global ocean, overlain by a dense, hydrogen-rich atmosphere. This type of planet was proposed relatively recently and is considered one of the most promising locations for the search for extraterrestrial life, as even under unusual conditions, stable temperatures and chemical processes favorable for microorganisms can exist in the deep ocean layers. Real interest in K2-18 b arose after the launch of the James Webb Space Telescope, which is capable of analyzing the chemical composition of the atmospheres of distant planets. As K2-18 b passes in front of its star, some of the starlight passes through its atmosphere, allowing us to determine what substances are present. Analysis revealed the presence of water vapor, methane, and carbon dioxide — molecules that play an important role in the chemistry of potentially habitable worlds. However, scientists did not detect any significant amounts of ammonia, which is also consistent with some models for the existence of a deep subatmospheric ocean. These discoveries make K2-18 b one of the most promising planets to search for signs of life outside the solar system. #exoplanet #earth #Astronomy #planets - @holvek