The planet – called HD 209458b – orbits 100 times closer to its home star than our Jovian neighbour, travelling in an astonishingly fast 3.5-day orbit. For comparison, Mercury – our solar system fastest planet – has an 88-day orbit.
Since HD 209458b is so close to the sun, the stellar winds are ripping the planet’s atmosphere apart. Scientists have used the Hubble’s Cosmic Origins Spectrograph to gather evidence that support the theory that its 1093C atmosphere is being ejected from its body at 35,406km/h.
According to astronomer Jeffrey Linsky, of the University of Colorado in Boulder:
Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like. We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. The most likely interpretation is that we have measured the velocity of material in a tail […]This large gas flow is likely gas swept up by the stellar wind to form the comet-like tail trailing the planet.
I don’t know about you, but I’m happy that there are so many new things to watch and discover out there. [NASA]