Timeline of the interstellar medium and intergalactic medium

  • 1848 - Lord Rosse studies M1 and names it the Crab Nebula
  • 1864 - William Huggins studies the spectrum of the Orion Nebula and shows that it is a cloud of gas
  • 1927 - Ira Bowen explains unidentified spectral lines from space as forbidden transition liness
  • 1930 - Robert Trumpler discovers absorption by interstellar dust by comparing the angular sizes and brightnesses of globular clusters
  • 1944 - Hendrik van de Hulst predicts the 21 cm hyperfine line of neutral interstellar hydrogen
  • 1951 - H.I. Ewen and Edward Purcell observe the 21 cm hyperfine line of neutral interstellar hydrogen
  • 1956 - Lyman Spitzer predicts coronal gas around the Milky Way
  • 1965 - James Gunn and Bruce Peterson use observations of the relatively low absorption of the blue component of the Lyman-alpha line from 3C9 to strongly constrain the density and ionization state of the intergalactic medium
  • 1969 - Lewis Snyder, David Buhl, Ben Zuckerman, and Patrick Palmer find interstellar formaldehyde
  • 1970 - Arno Penzias and Robert Wilson find interstellar carbon monoxide
  • 1970 - George Carruthers observes molecular hydrogen in space
  • 1977 - Christopher McKee and Jeremiah Ostriker propose a three component theory of the interstellar medium