Hydrogen Wall May Have Been Detected at the Edge of the Solar System

  NASA's New Horizons spacecraft has recently spotted an ultraviolet glow that appears to be emanating from near the edge of the solar system. According to a new study released by scientists working on the mission, this could be the long-sought wall of hydrogen that represents the boundary of our solar system where the sun's influence diminishes greatly.

  As the sun travels through our galaxy, it produces a constant stream of charged particles known as the solar wind. This inflates as a safety bubble around the solar system called the heliosphere. Beyond this bubble, uncharged hydrogen atoms in interstellar space should slow and accumulate when they collide with solar wind particles, creating scattered ultraviolet light.

  Signs of this light scattering were observed 30 years ago by the two Voyager spacecraft. New Horizons is the first spacecraft in a position to reaffirm the Voyagers' observations. For the last 7 years the spacecraft has made seven separate observations that appear to support the decades-old observations.
  “We’re seeing the threshold between being in the solar neighborhood and being in the galaxy,” said team member Leslie Young of the Southwest Research Institute, located in Boulder, Colorado.
  “It’s really exciting if these data are able to distinguish the hydrogen wall,” said physicist David McComas of Princeton University, who was not involved in the new work. 

Read the full study here: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078808 

Image Credit: Adler Planetarium/IBEX/NASA