Waterworlds seen as new tip in search for alien life

Scientists have identified a new type of planet that could support life.

Astronomers from the University of Cambridge say in the latest edition of The Astrophysical Journal, a peer-reviewed scientific publication that specializes in astrophysics and astronomy, that Hycean waterworlds are an important subtype of planetary ice worlds that have life-supporting potential.

While at first glance, with temperatures reaching 200 C, they appear inhospitable, the scientists say Hycean waterworlds that orbit stars without rotating on their axes could sustain life on their dark side.

And they contend that, by focusing attention on this new class of planet, life beyond our world could be detected in two to three years.

"Hycean planets open a whole new avenue in our search for life elsewhere," The Telegraph newspaper quoted lead researcher Nikku Madhusudhan, from Cambridge's Institute of Astronomy, as saying.

He and his team believe Hycean waterworlds, which are hot, ocean-covered planets with atmospheres that are rich in hydrogen, are far more likely to be home to alien life than those scientists are currently studying, which are in the so-called Goldilocks Zone around stars.

Those Goldilocks Zone planets -rocky Earthlike worlds that are neither too hot nor too cold to exclude liquid water－are far less common than Hycean waterworlds.

The team from the University of Cambridge says Hycean waterworlds can potentially support aquatic microbial life at far hotter and far colder temperatures than planets in the Goldilocks Zone.

Madhusudhan and his team based their findings on their analysis of a planet called K2-18b.

Anjali Piette, the study's co-author, told The Telegraph:"It's exciting that habitable conditions could exist on planets so different from Earth."

The Times newspaper noted that Hycean waterworlds are smaller than "ice giants" like Neptune and Uranus. They are thought to be too large, though, to have the rocky interiors of Mercury, Venus, Earth and Mars.

Astronomers have, so far, identified more than 4,000 Hycean waterworlds and believe there could be 100 billion throughout the Milky Way. In comparison, there are thought to be around 17 billion planets in the Milky Way that are rocky and similar in size to the Earth.

"A biosignature detection would transform our understanding of life in the universe," the Daily Mail newspaper quoted Madhusudhan as saying.