Water is ‘common’ on alien planets, scientists say in discovery that brings new hope in search for extraterrestrial life

Water is "common" on alien worlds according to the most extensive survey of the chemical compositions of planets ever conducted.

The discovery brings new hope in the quest to discover life on other planets.

Researchers at the University of Cambridge looked at 19 exoplanets, located outside our solar system, and found water vapour is common in their atmospheres.

Data was examined from a variety of worlds, including "mini-Neptunes" 10 times bigger than our Earth and "super-Jupiters" 600 times bigger.

Dr Nikku Madhusudhan, from the Institute of Astronomy at Cambridge, said: "We are seeing the first signs of chemical patterns in extra-terrestrial worlds, and we're seeing just how diverse they can be in terms of their chemical compositions."

Researchers also believe, like in our solar system, there is much more carbon relative to hydrogen in the atmospheres of exoplanets, meaning there should be large amounts of water.

But they discovered less water than expected, and there was great variety between the different kinds of worlds.

Water vapour was found in 14 of the 19 planets, and there was an abundance of sodium and potassium in six of them, found using different telescopes on Earth and in Space.

Luis Welbanks, lead author of the study and PhD student at the Institute of Astronomy, said: "Measuring the abundances of these chemicals in exoplanetary atmospheres is something extraordinary, considering that we have not been able to do the same for giant planets in our solar system yet, including Jupiter, our nearest gas giant neighbour."

He added: "Since Jupiter is so cold, any water vapour in its atmosphere would be condensed, making it difficult to measure.

"If the water abundance in Jupiter were found to be plentiful as predicted, it would imply that it formed in a different way to the exoplanets we looked at in the current study."