NGC 6822 was discovered by
E. E. Barnard in 1884 using a six-inch
refractor telescope.
Edwin Hubble, in the paper
N.G.C. 6822, A Remote Stellar System, identified 15 variable stars (11 of which were
Cepheids) of this galaxy. He also surveyed the galaxy's stars distribution down to magnitude 19.4. He provided spectral characteristics, luminosities and dimensions for the five brightest "
diffuse nebulae" (giant
H II regions) that included the
Bubble Nebula and the
Ring Nebula. He also computed the
absolute magnitude of the entire galaxy. Hubble's detection of eleven Cepheid variable stars was a milestone in
astronomy. Utilizing the
Cepheid Period-Luminosity relationship, Hubble determined a distance of . This was the first system beyond the Magellanic Clouds to have its distance determined. (Hubble continued this process with the
Andromeda Galaxy and the
Triangulum Galaxy). This distance to the galaxy was way beyond
Harlow Shapley's value of 300,000 light-years for the size of the
universe. In the paper, Hubble concluded the "
Great Debate" of 1920 between
Heber Curtis and Shapley over the scale of the universe and the nature of the "
spiral nebula". It soon became evident that all spiral nebulae were in fact
spiral galaxies far outside our own Milky Way. An analysis of Hubble's plates by
Susan Kayser in 1966 remained the most complete study of this galaxy until 2002. In 1977,
Paul W. Hodge extended the list of known H II regions in Barnard to 16. Today, there are over 150 of these regions catalogued in Barnard's Galaxy. ==Star formation==