Home > Timeline of knowledge about the interstellar 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 lines
• 19301930 is the common year starting on Wednesday. see link for calendar) Events January-February January 6 The first diesel-engine automobile trip is completed ( Indianapolis, Indiana, to New York City). January 27 Miguel Primo de Rivera resigns January 30 G - Robert Trumpler discovers absorption by interstellar dust by comparing the angular sizes and brightnesses of globular clusterA globular cluster is a spherical bundle of stars that orbits a galaxy as a satellite. Globular clusters are very tightly gravitationally bound, which gives them their spherical shape, and extremely dense (in relative terms) towards their core. Globular Cs
• 1944Events World War II January January 4 The Battle of Monte Cassino begins. January 5 Murder of Danish playwright Kaj Munck January 17 British forces, in Italy, cross the Garigliano River. January 20 The Royal Air Force drops 2,300 tons of bombs on Berlin; - Hendrik van de Hulst predicts the 21 cm hyperfine lineIn physics and astronomy, the 21 cm line is the name for a highly forbidden emission line of hydrogen. This emission line is often observed by radio astronomers to study both our own Galaxy and external galaxies. History During the 1930s, it was noticed t of neutral interstellar hydrogenhydrogen helium H Li Full table General Name, Symbol, NumberHydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1 , s Density, Hardness 0. 0899 kg/m3, NA Appearance colorless Atomic properties Atomic weight 1. 00794 amu Atomic radius (ca
• 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