K2-18B, an exoplanet discovered in 2015 by NASA's Kepler Space Telescope, is of great importance for the search for planets outside the Solar System that have the potential to harbor life. K2-18B has attracted attention in the scientific community as a planet thought to harbor Earth-like conditions, and particularly for the detection of methane and carbon dioxide in its atmosphere.

Discovery and Characteristics of K2-18B

K2-18B was discovered by the Kepler Space Telescope during the K2 discovery mission and is located approximately 124 light-years from Earth. K2-18B is a planet orbiting K2-18, a star similar to the Sun, and is located within that star's habitable zone. While there is no definitive information yet about the planet's surface and atmosphere, it is thought to be a super-Earth and its surface may have conditions that could harbor liquid water.

^{K2-18B Planet (BBC)}

Webb Telescope and New Discoveries

In April 2025, observations made by the James Webb Space Telescope revealed the detection of methane and carbon dioxide in K2-18B's atmosphere. This discovery provides an important clue that biosignatures may be present in the planet's atmosphere. Scientists suggest that gases such as methane and carbon dioxide could be produced by biological processes. This situation is of great importance for investigating K2-18B's potential to harbor life.

Biosignatures and the Possibility of Life

The methane and carbon dioxide detected in K2-18B's atmosphere present a significant biosignature possibility for scientists evaluating the planet's potential to harbor life. Methane on Earth primarily originates from biological sources, and carbon dioxide can be a byproduct of biological processes like photosynthesis. The presence of these gases strengthens the possibilities that traces of life could be found on the planet and that the planet is suitable for hosting life. However, methane and carbon dioxide can originate not only from biological but also from geological processes. Therefore, more observations are needed before drawing a definitive conclusion.

^{Atmospheric Composition of K2-18B Planet (NASA)}

Water and Life Possibilities

Studies on K2-18B's potential to harbor life have increased the possibilities regarding the presence of liquid water in the planet's atmosphere. According to NASA's latest research, K2-18B's surface may have conditions that support the presence of liquid water. Experts suggest that the planet, along with water vapor, atmospheric gases, and temperature conditions, may offer a favorable environment for life. However, it has not been confirmed whether liquid water exists on the planet's surface, and further research is needed on this matter.