Detecting a planet with a tail

Because a planet moves so close to its own star, its atmosphere is sucked out and forms a trail like a comet.

The illustration of the planet has its own tail and star.Photo: NASA .

National Geographic said the planet HD 209458b is made up primarily of gases. It is about 153 light-years from Earth and is about the size of Jupiter. This planet is so close to its own star that its year is only 3.5 days - shorter than the whole year of Mercury (88 days).

Thanks to the Hubble Space Telescope, the University of Colorado astronomer Cynthia Froning and colleagues discovered a trail of gas escaping from HD 209458b and heading towards Earth at a speed of about 35,400 km / h.

Astronomers believe that, because the distance from the star is so short, the gas layers of HD 209458b are constantly peeled off by the attraction of the individual star. That is the reason for its tail like a comet.

HD 209458b is losing about 36,000 kilograms of matter every day or a billion of the Earth's mass each year. Thus, theoretically it will disappear forever after a certain period of time. However, that disappearance will only happen after about 1,000 billion years.

'That time is longer than the life of a private star,' Froning said.

Froning admitted that the team has not identified the 'tail' length of HD 209458b. They also did not know when the streak began to form, but it was clear that the process had existed for several million years.