The spacecraft spotted UV light scattered across the farthest reaches of the solar system.
A NASA probe has detected traces of a ‘hydrogen wall’ surrounding our solar system, in an icy, asteroid-filled region of space beyond Pluto.
The New Horizons probe picked up an ultraviolet glow, which could be evidence of a wall of dense hydrogen between the solar system and interstellar space.
Leslie Young of the Southwest Research Institute said, ‘We’re seeing the threshold between being in the solar neighbourhood and being in the galaxy.’
The ‘wall’ is thought to be made of hydrogen atoms which ‘slow down’ when they reach the ‘heliopause’, where the solar wind of particles blasted out of the sun dies down.
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In measurements between 2007 and 2017, the New Horizons probe has detected an ultraviolet glow which echoes measurements taken by the Voyager probe 30 years ago.
The researchers write, ‘Both sets of data are best explained if the observed ultraviolet light is not only a result of the scattering of sunlight by hydrogen atoms within the solar system, but includes a substantial contribution from a distant source.
‘This distant source could be the signature of a wall of hydrogen, formed near where the interstellar wind encounters the solar wind.’