Humans have been searching for extraterrestrial life for decades, and now we finally have some clues – exoplanet K2-18b.
Scientists have discovered ideal conditions for life on a planet located 124 light-years away from Earth. This exoplanet is named K2-18b and was initially detected by the Kepler space telescope in 2015. Unlike a typical super-Earth, K2-18b has an extremely dense atmosphere, possibly with no solid surface. Instead, the potential for life may be hidden within its atmosphere.
You might wonder how we can detect signs of life on distant planets 124 light-years away when the Webb Space Telescope can’t even capture images of Pluto? The answer lies in the planet’s spectrum. The Webb telescope has identified dimethyl sulfide in the exoplanet K2-18b’s atmospheric spectrum. This gas molecule can only be produced by biological activities on Earth, such as marine life and terrestrial plants. The presence of dimethyl sulfide suggests the existence of life structures similar to those on Earth, possibly in the exoplanet’s oceans or even at its seabed, and what the Webb telescope has detected are the traces of their emissions.
However, as a planet with a mass 8.6 times that of Earth, K2-18b’s gravitational force is much stronger. This means that if there are organisms in its oceans with skeletons, they would be smaller and less massive, but their bone density would be higher than the creatures on present-day Earth, possibly resembling trilobites from Earth’s ancient oceans.
K2-18b, also known as EPIC 201912552 b, is an exoplanet outside the Solar System that orbits the red dwarf star K2-18, at a distance of 124 light-years from Earth. This planet was initially discovered through the Kepler program and later confirmed to have a mass 8.6 times that of Earth with an orbit of 33 days within the star’s habitable zone. Photo: Unbelievable
Unlike the Earth-Sun combination, K2-18b’s parent star is a low-mass red dwarf star, which means that K2-18b is very close to its parent star. Astronomers have found that it takes only 33 Earth days for K2-18b to orbit its parent star, meaning that a year on K2-18b is equivalent to only 33 Earth days.
Still, even in this scenario, there is a significant amount of liquid water on the surface of K2-18b to form oceans. Analysis of the atmospheric data from the James Webb Space Telescope shows that the water vapor concentration there could be as high as 50%. Thus, K2-18b is genuinely a water world, or it might even be a hydrogen-rich planet.
While the presence of water is a crucial discovery, it is not the sole determinant of a planet’s habitability. Scientists are still searching for specific molecules related to life, such as methane and CO2 – gases produced by life forms similar to those on Earth.
At the current moment, even though we can’t physically explore K2-18b in the near future, the observational data from the Webb Telescope has brought us closer to evidence of extraterrestrial life than ever before.
In fact, many scientists believe that while extraterrestrial life may be common in the universe, there may not be many forms of life that have evolved beyond primitive life and developed advanced civilizations, just like it took a long time for various life forms on Earth to emerge.
So, when human civilization reaches a technological level that allows us to travel to K2-18b in the future, we may very well encounter a world with simple life instead of an advanced extraterrestrial civilization with advanced technology.
Discovered since 2015, K2-18b is one of hundreds of planets with a mass of less than 10 times that of Earth found by NASA’s Kepler space telescope. In the decades to come, humanity will launch new space missions to discover hundreds more planets of this kind. Photo: ZME