Scientists have been able to calculate the colour of a planet 63 light years away and found that it bears a striking resemblance to Earth.
An artist’s impression of HD 189733b shows it would be a brilliant cobalt blue if seen from a short distance in space.
But although it looks cool astronomers say conditions there are hellish.
Temperatures on the exoplanet – a planet outside the Solar System – are said to be 1000C.
Winds blow at more than 4,000 mph, it rains slivers of silicate glass and the chances of life are extremely remote.
As there are no blue oceans the colour is thought to come from light scattered by silicate particles in the atmosphere.
Professor Frederic Pont from the University of Exeter, who led the international Hubble Space Telescope team, said: “Measuring its colour is a real first – we can actually imagine what this planet would look like if we were able to look at it directly.”
HD 189733b is a gas giant orbiting very close to its parent star, and its colour was calculated by measuring the light reflected from its surface.
This was a major breakthrough for astronomers, who have been able to determine the true colour of an exoplanet orbiting a star beyond the sun for the first time.
Tom Evans from Oxford University, co-author of the findings, said: “We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star.
“From this, we can gather that the planet is blue, because the signal remained constant at the other colours we measured.”
The dazzling blue HD 189733b is part of a group of exoplanets known as “hot Jupiters”.
These are huge planets similar to the gas giants in our solar system but which lie very close to their parent stars.