Atmosphere

That space voyeur we call Hubble was, in 2003, peeking at an extrasolar "Hot Jupiter". Hot Jupiters are gas giants that orbit very closely to their stars. Because they are so close, they revolve around the stars fairly quickly. The larger size and frequency of revolutions makes these planets easier to detect from Earth. Most of the extrasolar planets we know about are Hot Jupiters.

The analysis of the 2003 observations indicates that the atmosphere of one Hot Jupiter is in fact being "melted off" by it's proximity to the star. The atmosphere trails behind the orbiting planet like a comet giving it... a bit of tail.