The rate at which scientists are discovering exoplanets has rocketed in recent years yet we still now very little about them.
Because of the distances involved the only way we can know they are there is to detect tiny fluctuations in the light given off by the stars they orbit as they pass in front of them.
Now for the first time the Hubble Space Telescope has pinpointed the visible colour of an exoplanet.
HD 189733b is a rather striking shade of cobalt blue.
The relative closeness of the the planet allowed astronomers to distinguish between the light reflected off it and that emitted by its star.
It may look beautiful but it is in fact a gas giant 63 light-years away most likely with an atmosphere laced with deadly silicate which would condense into glass hurled by winds of 4,000mph.