As far back as 1855 Observations were made of distant stars which suggested that they might in fact have planets orbiting around them. But the first Published discovery of a planet orbiting a star outside of our own solar system to later receive confirmation was not made until 1988 when Canadian astronomers Bruce Campbell, G. A. H. Walker, and S. Yang made radial-velocity observations which suggested that there was a planet orbiting the star Gamma Cephei. The trio's observations would eventually be confirmed in 2002.
Today projects like Trappist, a new robotic telescope from the ESO designed to detect exoplanets, and Keppler a NASA space observatory launched in March of 2009, have helped us to detect over 450 planets orbiting distant stars. One such planet is Osiris or HD 209458b which orbits the star HD 209458 in the Pegasus constellation 150 light years away from earth.
Osiris was first spotted in 1999 and additional observation of the planet have since confirmed that the gas giant has not only water vapor in it's atmosphere but methane as well as carbon dioxide and that the Planet's orbit is a mere one eighth the radius of Mercury's. Meaning, Osiris revolves around it's own sun in just 3.5 days leaving it with an estimated surface temperature of 1000 degrees Celsius. Now new observations of Osiris made by the Hubble Space Telescope's Cosmic Origins Spectrograph have confirmed that the consequent evaporation of the planet's atmosphere mean the gas giant leaves behind itself a tail like a comet as it's atmosphere is slowly burned away. -CAINE-
Links And Additional Content
You can find out more about Osiris by visiting this article on the discovery blog: 80beats, which was my main source for this story. Or if you just want more info on exoplanets in general check out NASA's PlanetQuest site which is full of pictures, multimedia presentations and other cool stuff. But my personal favorite link of the day, the Exoplanetology blog right here blogspot which I stumbled upon while googling for this entry and ended up being distracted by for quite some time.