THE halo of hot gas surrounding the Milky Way was blasted out of our galaxy
by supernovae explosions. Astronomers have for several years known about the
gas—which stretches up to 10 000 light years above and below the galactic
plane—but had no idea how it got there.
Launched last summer, NASA’s Far Ultraviolet Spectroscopic Explorer has
recorded ionised oxygen atoms in the ultraviolet spectra of the halo, proving
the explosion theory.
“The only way to make the observed amount of [ionised oxygen] is through
collision with the blast waves from exploding stars,” Blair Savage of the
University of…
