A scorched alien planet is flying so close to its parent star that its atmosphere is being swept off it in a glowing tail like some sort of giant comet, NASA announced Thursday. The existence of the planet and its strange tail, which was suggested in previous studies, was confirmed recently by NASA's Hubble Space Telescope.
These new observations of the gas giant planet, called HD 209458b, suggest strong winds from its nearby star are blowing the atmosphere off the scorched world and shaping it into a comet-like tail. "Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like," said astronomer Jeffrey Linsky of the University of Colorado in Boulder, leader of the study.
"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 planet orbits its star from a distance of about 4 million miles (7 million km) 100 times closer than Jupiter circles the sun yet the mass of HD 209458b is only slightly less than Jupiter. HD 209458b zips around its star in a short 3.5 days. In contrast, our solar system's fastest planet, Mercury, orbits the sun in 88 days. [ Gallery: Strangest Alien Planets ]
At such close quarters with its star, HD 209458b's atmosphere is a scorching 2,000 degrees Fahrenheit (1,093 Celsius). Past studies have suggested that it is losing about 10,000 tons of gas every second as material is blown off by its parent star. Eventually, it might be stripped entirely of its gas envelope, leaving behind a liquid core of lava. Even so, it will be a long while before the planet is completely destroyed.
"It will take about a trillion years for the planet to evaporate," Linsky said. The planet is located 153 light-years from Earth. This world was the first of the few known extrasolar planets that seen to be passing in front of, or transiting, their stars.