Astronomers have discovered a new steamy planet which is six times bigger than Earth and containing 75 per cent water.

The planet is believed to be too hot to sustain Earth-type life has been discovered just 40 light years away by scientists at Harvard-Smithsonian Center for Astrophysics.

According to them, the ‘waterworld’, which orbits a faint star in 38 hours at a distance of just 1.3 million miles, has also an atmosphere and it is more Earth-like than any ’exoplanet’ previously found outside the Solar System.

“Despite its hot temperature, this appears to be a waterworld,” said Harvard-Smithsonian Center researcher Zachory Berta, who discovered the planet.

“It is much smaller, cooler and more Earth-like than any other known exoplanet.”

The planet was found circling the star GJ1214 with an array of small ground-based telescopes no larger than those used by many amateurs under the MEarth Project.

The MEarth Project employs eight identical 16-inch diameter telescopes monitoring a 2,000 red dwarf stars. Red dwarfs are the most common type of star in the Milky Way galaxy, The Daily Mail reported.

The planet is classified as a ‘super-Earth’, half-way in size between small rocky planets such as the Earth and ice giants similar to Uranus and Neptune.

Although its parent star is a dim ‘red dwarf’ 3,000 times less bright than our sun, it hugs the star so closely that its surface temperature is 200C.

The scientists believe something besides the planet’s surface must be blocking light from the parent star — probably a surrounding atmosphere that may contain hydrogen and helium.

Turning the Hubble Space Telescope towards the planet may allow astronomers to discover its composition.

MEarth Project head Dr David Charbonneau said: “Since this planet is so close to Earth, Hubble should be able to detect the atmosphere and determine what it’s made of.

“That will make it the first super-Earth with a confirmed atmosphere — even though that atmosphere probably won’t be hospitable to life as we know it.”

The discovery was reported in the journal Nature.

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