Discovery of ‘water worlds’ boosts hunt for aliens
'Exoplanets' outside our solar system are likely to contain an abundance of water, scientists have found
The chances of finding alien organisms have been boosted by the discovery of hundreds of “water worlds” capable of supporting life.
New analysis by Harvard University estimates that one in three “exoplanets” outside our solar system that are larger than Earth are likely to contain an abundance of water.
The scientists say the planets that are two to four times bigger than Earth that have the best chance of supporting life.Analysis of data from the exoplanet-hunting Kepler Space Telescope and the Gaia mission indicates half their weight may be water, either flowing or frozen.
In comparison, the amount of water on Earth makes up just 0.02% of its complete mass.Lead researcher Dr Li Zeng said: “It was a huge surprise to realise that there must be so many water worlds.”
Exoplanets were first discovered in 1992 and since then about 4,000 have been confirmed to exist.
Scientists believe they fall into two broad categories: those with a planetary radius averaging around one and a half times the size of Earth, or two and a half times.
Now the group of international scientists has developed a model of their internal structure, based on their recent mass and radius measurements from the Gaia satellite.“We have looked at how mass relates to radius, and developed a model which might explain the relationship,” said Zeng.
The model indicates that the smaller planets tend to be rocky planets, with typically five times as much mass as Earth.The larger ones have about 10 times more mass, and “are probably water worlds”, said Zeng.
Presenting the findings at the Goldschmidt conference in Boston, he explained: “This is water, but not as commonly found here on Earth.
“Their surface temperature is expected to be in the 200- to 500-degree celsius range.
“Their surface may be shrouded in a water vapour-dominated atmosphere, with a liquid-water layer underneath.”
– © The Daily Telegraph
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