Astronomers Say Azure Blue Exoplanet HD 189733b is Not Like Earth

Posted on July 11, 2013

Astronomers using the NASA/ESA Hubble Space Telescope have determined that the exoplanet HD 189733b has a deep azure blue color similar to the Earth. An artist's interpretation of the planet is pictured above. This is the first time an exoplanet's visible color has been determined.

The planet, a huge gas giant, is located 63 light-years away. The deep blue color is about the only thing it has in common with Earth. Astronomers say in a release that the planet's atmosphere is scorching with a temperature of over 1000 degrees Celsius. It also rains glass sideways on HD 189733b. The glass is carried by howling 7000 kilometer-per-hour winds.

Frederic Pont of the University of Exeter, UK, leader of the Hubble observing program and an author of the research paper, said in a statement, "This planet has been studied well in the past, both by ourselves and other teams. 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."

The astronomers say the planet's azure blue colour does not come from the reflection of an ocean, but is due to a hazy, turbulent atmosphere thought to be laced with silicate particles, which scatter blue light.

Tom Evans of the University of Oxford, UK, first author of the paper, said in a statement, "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."

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