Here on Planet Earth, when solar flares head in our direction, it can wreak havoc on our sensitive electronic equipment. Satellite transmissions can be interrupted, whole satellites can be taken offline, low level electromagnetic pulses can disrupt even sensitive equipment here on terra-firma.
But elsewhere in the universe, solar flares can have significantly more severe consequences, as is the case for exoplanet HD 189733b. This planet orbits closely enough to its host star that it completes an entire orbit – a solar year, in other words – in a mere 2.2 Earth days. There are 165.9 HD 189733b years for every one Earth year.
And as the Hubble telescope observed, such a close orbit means the planet has very little to defend its atmosphere from the stripping effects of solar radiation. Scientists discovered a stream of the planet’s atmosphere exiting the planet at a rate of nearly 300,000mph, then discovered that the host star, HD 189733A, had let loose an X-ray flare that was powerful enough to have been the culprit.
How many times can that happen before the planet loses atmosphere altogether? Hard to say and there is no indication how common or uncommon the scientists think such an event might be. Science may have born witness to a once-in-an-eon event, for all we know. But HD 189733b is a gas giant about fourteen percent larger than Jupiter, so its got some reserves. Here is a NASA video which dramatizes the event: