Friday, June 29, 2012

Reason #225: HD 189733b

Thanks to the Hubble Space Telescope, researchers have been able to witness for the first time changes in an exoplanet' atmosphere caused by a solar flare--which is a big accomplishment purely in terms of our ability to detect extrasolar activity, but also has the potential to teach us more about how solar flares here in our own system can affect the atmosphere of Earth.

 HD 189733b, first discovered in 2005, is (or was) a gas giant with 14 percent more mass even than Jupiter, yet it orbits its sun from only three million miles away, or twelve times closer than does Mercury in our system.

So when a massive eruption was detected coming from its star just hours before a scheduled transit (when the planet passes between the star and Earth, thereby allowing us to take measurements of it), scientists quickly realized that the planet's atmosphere was basically evaporating--rocketing away at a rate of one thousand tons per second.

Even when taking into account its much larger size, the amount of X-rays HD 189733b would have absorbed during the flare up were measured to be around three million times more than the Earth does during even the worst solar flares we've classified thus far.

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