H2-NO: Water blow in the hunt for Earth-like planets

No place like home: Blow in hunt for Earth-like planets Credit: PA

The hunt for planets similar to the Earth could be hampered by low water levels, Cambridge scientists have said.

Three planets which orbit stars similar to the sun had been seen as ideal candidates for detecting water vapour - a key characteristic of Earth-like climates.

But a team of astronomers using Nasa's Hubble Space Telescope studying HD 189733b, HD 209458b, and WASP-12b - which are between 60 and 900 light-years away, with temperatures ranging from 900 to 2200C - have found the planets are virtually dry.

Scientists from the Institute of Astronomy at the University of Cambridge said it highlighted the challenges in searching for planets capable of sustaining life.

They found water levels which are only one-tenth to one-thousandth of the amount predicted.

Dr Nikku Madhusudhan of the University of Cambridge said

"These very hot planets with large atmospheres orbit some of our nearest stars, making them the best possible candidates for measuring water levels, and yet the levels we found were much lower than expected. "These results show just how challenging it could be to detect water on Earth-like exo-planets in our search for potential life elsewhere. "We expected these planets to have lots of water in their atmospheres. We have to revisit planet formation and migration models of giant planets, especially hot Jupiters, to investigate how they're formed. There are so many things we still don't understand about exo-planets - this opens up a new chapter in understanding how planets and solar systems form."

– Dr Nikku Madhusudhan