Are There Aliens Broadcasting from Hycean World K2-18b? Astronomers Just Listened In

If you’ve been following exoplanet research over the last couple of years, you’ve definitely heard of K2-18b. Located 124 light years away in the constellation Leo, it’s attracted a lot of attention as it sits squarely in its red dwarf host star’s habitable zone, and measurements of the James Webb Space Telescope show its atmosphere is rich in carbon dioxide and methane. It’s one of the prime candidates for a “Hycean” world – one where a thick hydrogen-rich atmosphere covers a global liquid water ocean. It is such an intriguing target for Search for Extraterrestrial Intelligence (SETI) researchers that they turned two of the most powerful radio telescopes in the world to watch K2-18b’s system. A recent paper, available in pre-print on arXiv, shows that there is likely no artificial narrow-band radio signals that are equivalent to our technology level coming from the planet, despite millions of potential hits.