But the colour is the only way planet HD 189733b resembles the Earth, as the Telegraph reports. The planet is a gas giant, with temperatures reaching over 1,000C (1832F). It also rains glass sideways in winds that can hit over 7,000 kilometres per hour.
As reported by the Independent, the blue colour comes thanks to the planet’s liquid glass storms. HD 189733b is located in the constellation of Vulpecula, some 63 light years away from Earth.
The study, published in Astrophysical Journal Letters, was the first of its kind, allowing scientists for the first time to determine the colour of a planet that would otherwise appear as only a blur on the Hubble telescope.
“This planet has been studied well in the past, both by ourselves and other teams,” said professor Frédéric Pont, one of the paper’s authors. “But 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.”
As the Hubble website explains, scientists determined HD 189733b’s colour by measuring its albedo, or the measurement of how much light reflects off of the planet’s surface.
Using the Hubble telescope, the team looked at the planet as it orbited around its star. When the planet passed directly behind the star, the team noticed that HD 189733b’s blue light had dropped significantly.
“We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star,” explained Tom Evans of the University of Oxford, UK, and first author of the paper. “From this, we can gather that the planet is blue, because the signal remained constant at the other colours we measured.”
The planet is known in space terminology as a “hot Jupiter,” large gas giants that orbit close to their stars. The study of this azure planet may aid scientists in finding more “hot Jupiters” in the future.
