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New ‘waterworlds’ could make waves in humanity’s search for alien life, say experts from research

An artist’s impression of the so-called Hycean waterworlds, which are hotter than Earth but may still have conditions conducive to some aquatic microbial life CREDIT: Amanda Smith/University of Cambridge/PA Wire

A new classification of planets, so-called Hycean water worlds, maybe humanity’s best bet at finding a world that can sustain life, according to a new study. Astronomers from the University of Cambridge defined this new type of planet and believe focusing on them could enable alien lifeforms to be identified within three years. The search for life beyond Earth has thus far been a fruitless endeavour, with scientists now trying to find distant planets orbiting mysterious stars that they think could, perhaps, under the right conditions, harbour primitive life.

So far, efforts have centred around identifying a world similar to Earth, the one place we know life does thrive. This has entailed looking for rocky planets which are at just the right temperature that liquid water can exist on the surface in the “Goldilocks Zone”. However, analysis from Cambridge researchers has identified Hyceans – hot, ocean-covered planets with hydrogen-rich atmospheres more abundant than Earth-like worlds – may also be a promising option.

'A whole new avenue'

Dr Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research, said: “Hycean planets open a whole, new avenue in our search for life elsewhere.” These words, according to the researchers, are bigger and hotter than Earth but may still have conditions conducive to some aquatic microbial life. The planets also allow for a far wider habitable zone compared to Earth-like planets. This means that they could still support life even though they lie outside the range where a planet similar to Earth would need to be in order to be habitable.

The confidence that Hycean planets could break the deadlock in the pursuit of alien life comes from findings from Dr Madhusudhan’s team on a mini-Neptune planet called K2-18b. Dr Madhusudhan said: “Essentially when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start. But we think Hycean planets offer a better chance of finding several trace biosignatures.”

Co-author Anjali Piette, also from the University of Cambridge, added: “It’s exciting that habitable conditions could exist on planets so different from Earth.” The findings are reported in The Astrophysical Journal.

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