Scientists believe a mysterious phenomenon at the edge of the solar system could be a giant ‘wall’ made up of hydrogen atoms.
NASA’s New Horizons spacecraft launched in January 2006 and has been helping scientists understand worlds at the edge of our solar system ever since.
And now its focus has turned to a possible hydrogen wall right at the edge of our solar system, approximately 100 times further from the Sun than Earth where particles from the Sun and interstellar space interact.
In particular, the area sees uncharged hydrogen atoms from interstellar space interact with charged particles from the Sun, IFL Science reports.
It is thought that at the point where the two interact, known as the heliopause, there is a build-up of hydrogen. This then creates a ‘wall’, which scatters ultraviolet light in a distinctive way.
This wall was first discovered approximately 30 years ago by NASA’s Voyager spacecrafts, but New Horizons is the first spacecraft since which has been in a position to confirm its findings.
A paper describing its findings was published in Geophysical Research Letters and explains:
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, or could be more distant.
As reported by Science News, New Horizons scanned the sky seven times between 2007 and 2017; in that time, it witnessed more ultraviolet light further away from the sun than we would expect to see if there is no wall.
Dr Leslie Young from the Southwest Research Institute in Colorado, and one of the co-authors on the paper, told Science News:
We’re seeing the threshold between being in the solar neighborhood and being in the galaxy.
And space scientist David McComas, of Princeton University, said:
It’s really exciting if these data are able to distinguish the hydrogen wall.
However, the research team also iterates the light could be from an unknown source further away in the galaxy, rather than a hydrogen wall.
In an attempt to confirm their findings, New Horizons will continue looking for the wall approximately two times every year.
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