Your report that water vapour, perhaps even rain, has been detected in a planet in the so-called Goldilocks zone of a distant star is of no surprise because water is a common stable molecule that is found throughout the universe (Discovery of water raises hopes of life on faraway super-Earth, 12 September).
Whether this planet harbours life or not depends on how hugely improbable the startup of life really is, not just on Earth but anywhere in the cosmos.
Over several decades, my colleagues, collaborators (including the late Sir Fred Hoyle) and I have published arguments to say that the spread of life (panspermia) from a single cosmic event of origination is the most likely answer.
In this case life must surely take root on every habitable planet, and that includes K2-18b, at a distance of 110 light years away.
Prof Chandra Wickramasinghe
Cardiff
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