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Blue-Hot Planet

December 2, 2013

Like Earth, a world in another star system could fairly be described as “the blue planet.” It’s not a place you’d want to stop by for a quick swim, though. The blue comes not from water, but from bits of glass forged high in the planet’s atmosphere.

HD 189733b orbits a star in Vulpecula, the fox, which is low in the west as night falls. The constellation is between the stars Deneb and Altair, the two points that form the left side of the bright Summer Triangle.

The planet is too far and too small to see directly. But every couple of days it passes in front of, then behind, its parent star. Carefully studying how that changes the qualities of the star’s light can reveal details about conditions on the planet.

The planet is a bit bigger and heavier than Jupiter, the giant of our own solar system. But it’s quite close to its parent star, so its dayside temperature is about 2,000 degrees Fahrenheit. But temperatures on the nightside are hundreds of degrees cooler, which should stir up 4500-mile-an-hour winds.

Silicon-rich minerals may condense in the planet’s hot upper atmosphere, forming tiny bits of glass. These beads would reflect blue light while absorbing other colors, giving the planet its deep blue appearance.

A couple of years ago, astronomers saw a plume of gas blowing away from the planet, most likely pushed into space by a giant burst of X-rays from the star — eroding some of the atmosphere of this blue-hot planet.


Script by Damond Benningfield, Copyright 2013

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