The Fermi glow consists of ultraviolet-glowing particles, mostly hydrogen, originating from the Solar System's bow shock, created when light from stars and the Sun enter the region between the heliopause and the interstellar medium"A Glowing Discovery at the Forefront of Our Plunge Through Space ". SPACE.com. 15 March 2000. and undergo Fermi acceleration, bouncing around the transition area several times, gaining energy via collisions with atoms of the interstellar medium. The first evidence of the Fermi glow, and hence the bow shock, was obtained with the help from Voyager 1 and the Hubble Space Telescope.
In 2012, data collected from the Interstellar Boundary Explorer satellite and Voyager 1 and 2 indicated that the Sun isn't moving fast enough through its current interstellar environment to have a bow shock.
See also Heliosphere Heliopause Termination shock Bow shock
References