Water detected in atmosphere of planet orbiting in habitable zone

Image: ESA/Hubble, M. Kornmesser

Astronomers have detected water vapour in the atmosphere of another planet in a habitable zone for the first time.

The planet, known as K2-18b, is twice the size and eight times the mass of Earth, and 110 light-years away.

The planet sits in the habitable ‘Goldilocks zone’ around the star it orbits, receiving enough light and warmth to allow liquid water to exist.

Professor Alan Duffy, Astronomer at Swinburne University, said he’s “excited” about the discovery.

“It’s an incredible achievement to detect the planet as it passes between us and this distant star over 100 light-years away,” he told 3AW’s Tom Elliott.

“We’ve seen water in the atmosphere, but it’s a very thick, very heavy atmosphere.

“This isn’t so much an earth-like world as a mini Neptune.”

Mr Duffy said it may rain on the planet, but there is certainly no ocean or anything similar.

“It’s got water in its air but it’s almost certainly got no surface … where you could find that water pooling as a liquid in lakes and oceans, and that’s of course, what we need for life, at least as far as we’re aware,” he said.

But we will have to wait for new technology before investigating further.

The planned successor to the Hubble Space Telescope, which discovered the water in K2-18B’s atmosphere, may shed some light on the situation.

“In the next five or ten years the James Webb Space Telescope and others are being launched that are designed to … find more details of the atmosphere.”

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