气体行星独特的运动轨迹使其形成了彗星尾巴(有（在线收听）

A planet called HD 209458b, aka Osiris, orbits its star so closely that it is losing some of its atmosphere to the stellar wind. It may thus have a cometary tail

Whaddya get when you cross a planet with a comet? Well, HD 209458b looks like a candidate. It’s a gas giant planet also called Osiris, and it’s orbiting so close to its star that some of its atmosphere gets blown away by the stellar wind. Astronomers think that it may then have a tail like a comet’s.

The researchers studied the odd object using the Hubble Space Telescope and reported their finding in the July 10th issue of The Astrophysical Journal.

The planet is about 153 light-years from Earth, and weighs a bit less than Jupiter. But its zippy orbit is a hundred times closer to its star than Jupiter’s is.

Astronomers got information about the planet by observing its effect on its star’s light when it moved in front of the star from our point of view. They found that most of the gas being driven away from the planet by its star was moving at 22,000 miles per hour. But don’t worry about the planet disappearing entirely any time soon. The current best estimate to complete the vaporization: a trillion years.