Timeline of knowledge about the interstellar and intergalactic medium
Encyclopedia
Timeline
Timeline
A timeline is a way of displaying a list of events in chronological order, sometimes described as a project artifact . It is typically a graphic design showing a long bar labeled with dates alongside itself and events labeled on points where they would have happened.-Uses of timelines:Timelines...

 of the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

 and intergalactic medium

  • 1848 — Lord Rosse
    William Parsons, 3rd Earl of Rosse
    William Parsons, 3rd Earl of Rosse, Knight of the Order of St Patrick was an Irish astronomer who had several telescopes built. His 72-inch telescope "Leviathan", built 1845, was the world's largest telescope until the early 20th century.-Life:He was born in Yorkshire, England, in the city of...

     studies M1
    Messier object
    The Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. The original motivation of the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets...

     and names it the Crab Nebula
    Crab Nebula
    The Crab Nebula  is a supernova remnant and pulsar wind nebula in the constellation of Taurus...

  • 1864 — William Huggins
    William Huggins
    Sir William Huggins, OM, KCB, FRS was an English amateur astronomer best known for his pioneering work in astronomical spectroscopy.-Biography:...

     studies the spectrum of the Orion Nebula
    Orion Nebula
    The Orion Nebula is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light...

     and shows that it is a cloud of gas
  • 1927 — Ira Bowen
    Ira Sprague Bowen
    Ira Sprague Bowen was an American astronomer. In 1927 he discovered that nebulium was not really a chemical element but instead doubly ionized oxygen.-Life and work:...

     explains unidentified spectral line
    Spectral line
    A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...

    s from space as forbidden transition lines
  • 1930 — Robert Trumpler
    Robert Julius Trumpler
    Robert Julius Trumpler was a Swiss-American astronomer....

     discovers absorption by interstellar dust by comparing the angular sizes and brightnesses of globular cluster
    Globular cluster
    A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...

    s
  • 1944 — Hendrik van de Hulst
    Hendrik C. van de Hulst
    Hendrik Christoffel "Henk" van de Hulst FRS was a Dutch astronomer and mathematician....

     predicts the 21 cm hyperfine line of neutral interstellar hydrogen
    Hydrogen
    Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

  • 1951 — H.I. Ewen and Edward Purcell
    Edward Mills Purcell
    Edward Mills Purcell was an American physicist who shared the 1952 Nobel Prize for Physics for his independent discovery of nuclear magnetic resonance in liquids and in solids. Nuclear magnetic resonance has become widely used to study the molecular structure of pure materials and the...

     observe the 21 cm hyperfine line of neutral interstellar hydrogen
  • 1956 — Lyman Spitzer
    Lyman Spitzer
    Lyman Strong Spitzer, Jr. was an American theoretical physicist and astronomer best known for his research in star formation, plasma physics, and in 1946, for conceiving the idea of telescopes operating in outer space...

     predicts coronal gas around the Milky Way
    Milky Way
    The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

  • 1965 — James Gunn and Bruce Peterson
    Bruce Peterson
    Bruce Peterson was a test pilot for NASA.A native of Washburn, North Dakota, he attended the University of California at Los Angeles, and California Polytechnic State University...

     use observations of the relatively low absorption of the blue component of the Lyman-alpha line
    Lyman-alpha line
    In physics, the Lyman-alpha line, sometimes written as Ly-\alpha line, is a spectral line of hydrogen, or more generally of one-electron ions, in the Lyman series, emitted when the electron falls from the n = 2 orbital to the n = 1 orbital, where n is the principal quantum number...

     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
    Interstellar formaldehyde
    Interstellar formaldehyde was first discovered in 1969 by L. Snyder et al.. using the National Radio Astronomy Observatory. Formaldehyde was detected by means of the 111 - 110 ground state rotational transition at 4830 MHz.-Initial discovery:Formaldehyde was first discovered in interstellar...

  • 1970 — Arno Penzias
    Arno Allan Penzias
    Arno Allan Penzias is an American physicist and Nobel laureate in physics.-Early life and education:Penzias was born in Munich, Germany. At age six he was among the Jewish children evacuated to Britain as part of the Kindertransport rescue operation...

     and Robert Wilson
    Robert Woodrow Wilson
    For the American President, see Woodrow Wilson.Robert Woodrow Wilson is an American astronomer, 1978 Nobel laureate in physics, who with Arno Allan Penzias discovered in 1964 the cosmic microwave background radiation...

     find interstellar carbon monoxide
    Carbon monoxide
    Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

  • 1970 — George Carruthers observes molecular hydrogen in space
  • 1977 — Christopher McKee
    Christopher McKee
    Christopher Fulton McKee is an astrophysicist.McKee obtained a Ph.D. from the University of California, Berkeley in 1970 under advisor George B. Field. In 1974, he was appointed Professor of Physics and Astronomy, University of California at Berkeley. He is a member of the National Academy of...

     and Jeremiah Ostriker
    Jeremiah P. Ostriker
    Jeremiah Paul Ostriker is an astrophysicist at Princeton University. He received his B.A. from Harvard, his Ph.D at the University of Chicago, and then carried out post-doctoral work at the University of Cambridge. From 1971 to 1995, Ostriker was a professor at Princeton, and served as Provost...

     propose a three component theory of the interstellar medium
  • 1990 — Foreground "contamination" data from the COBE
    COBE
    The COsmic Background Explorer , also referred to as Explorer 66, was a satellite dedicated to cosmology. Its goals were to investigate the cosmic microwave background radiation of the universe and provide measurements that would help shape our understanding of the cosmos.This work provided...

     spacecraft provides the first all-sky map of the ISM in microwave
    Microwave
    Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

    bands.
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