Astronomers are perplexed by a strange young planet so close to its parent star that its atmosphere is evaporating and its orbit is changing in unpredictable ways.

The planet AU Microscopii b (AU Mic b), according to scientists from Nasa’s Goddard Space Flight Center, is showing clear signs of atmospheric loss with the its hydrogen-rich atmosphere puffing out in front of the planet, like a headlight on a fast-bound train.

“We’ve never seen atmospheric escape go from completely not detectable to very detectable over such a short period when a planet passes in front of its star,” study co-author Keighley Rockcliffe said.

“We were really expecting something very predictable, repeatable. But it turned out to be weird. When I first saw this, I thought ‘That can’t be right,’” Dr Rockcliffe said.

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