Astronomers detect exoplanet using Hubble Space Telescope’s light-splitting ultraviolet spectrograph

Astronomers have spotted Gliese 436b, a planet about the size of Neptune located about 30 light years from Earth.

The planet is situated 33 times closer to its parent star called Gliese 436 than Earth. It passed in front of its parent star in December 2012, June 2013 and June 2014. It is losing its atmosphere, forming a fat, comet-like tail in the process.

A huge and asymmetrical spike of hydrogen cloud has been found by the scientists. The hydrogen is likely caused by a massive hydrogen cloud surrounding and trailing the planet.

The cloud, which is about 50 times the size of the parent star, is expanding into space and giving the planet the look of a comet with a tail.

David Ehrenreich, with the Observatory of the University of Geneva said, "This cloud of hydrogen is very spectacular. Although the evaporation rate doesn't threaten the planet right now, we know that the star, a faint red dwarf, was more active in the past".

The cloud was spotted as hydrogen absorbed the ultraviolet light of the parent star and reflected it back to Hubble. This kind of evaporation may have happened in the early history of our own Solar System.

According to the estimation of scientists, 436b is losing more than a ton of hydrogen every second from its atmosphere. However, it actually works out to about 0.1% of its total mass every billion years. The study was published in the journal Nature.