Sixty-five Years of Discovery

1935 Hayden Planetarium opens (October)

1937 Grote Reber begins construction of backyard radio telescope, with which he makes first radio map of Milky Way

1938 Fritz Zwicky suggests galaxy clusters are basic building blocks of universe

Hans Bethe and Carl-Friedrich von Weizsacker independently work out theory of nucleosynthesis in interior of stars

1942 Radio waves from Sun first detected

1946 Radio waves outside Milky Way first detected

Ultraviolet radiation from Sun first detected

1948 200-inch Hale telescope at Mount Palomar completed

Ralph Alpher, George Gamow, and Robert Herman predict existence of cosmic background radiation and develop new model of formation of universe (the big bang)

X rays from Sun first detected

1949 Radio waves from individual galaxy beyond Milky Way first detected

1950 Jan Oort proposes distant reservoir of comets (Oort Cloud)

1952 Walter Baade revises Edwin Hubble's scale for universe, doubling its age and distances

1953 Murray Gell-Mann proposes new quantum property: strangeness

1957 Launching of Sputnik 1, first artificial satellite

Geoffrey Burbidge, Margaret Burbidge, William Fowler, and Fred Hoyle--as well as Alastair G. W. Cameron, independently--describe how nuclear reactions in stars synthesize elements heavier than helium

1958 George Abell publishes catalog of galaxy clusters

Jan Oort and colleagues map spiral arms of Milky Way galaxy using radio waves

1959 Luna 1 becomes first spacecraft to leave Earth's gravitational field

1960 Allan Sandage and Thomas Matthews discover quasars

1961 First cosmonaut, Yuri Gagarin, orbits Earth

Sheldon Glashow proposes electromagnetic and weak forces are aspects of single variety of interaction

1962 American astronaut John Glenn orbits Earth

Mariner 2 makes first successful planetary flyby (of Venus)

X rays beyond Solar System first detected

1963 Maarten Schmidt discovers quasars are most distant objects in universe

1964 Murray Gell-Mann and George Zweig independently propose existence of fundamental particles that Gell-Mann calls quarks

1965 Mariner 4 makes first Mars flyby

Arno Penzias and Robert Wilson discover cosmic background radiation, validating big bang theory

Alexei Leonov takes first space walk

1967 Jocelyn Bell and Anthony Hewish discover pulsars

First gamma-ray burst detected

1968 Apollo 8 becomes first manned spacecraft to leave Earth's gravitational field

1969 Neil Armstrong becomes first person to set foot on Moon

1972 Alar and Juri Toomre publish theory on evolution of galaxies

1973 Pioneer 10 makes first Jupiter flyby

Mariner 10 makes first Mercury flyby

Stephen Hawking shows black holes can radiate energy as subatomic particles

Binary pulsar discovered

1976 Viking 1 and Viking 2 land on Mars

1977 Rings of Uranus discovered

1978 Pluto's moon, Charon, discovered

1979 Gravitational lens first sighted

1980 Alan Guth proposes inflationary era of universe

1981 First space shuttle launched

Andrei Linde and, independently, Paul Steinhardt and Andreas Albrecht refine inflation theory

1982 Millisecond pulsar discovered

1983 Pioneer 10 leaves Solar System

Electroweak unified theory verified at CERN

1986 Margaret Geller, John Huchra, and Valerie de Lapparent publish three-dimensional map of universe, revealing walls of galaxies and intervening voids

1987 Supernova 1987A--brightest supernova in four centuries--explodes

1990 Hubble Space Telescope deployed

1991 Compton Gamma Ray Observatory deployed

1992 10-meter Keck telescope, world's largest reflector, goes into operation

Ripples in cosmic background radiation discovered as predicted, providing glimpse of seeds from which universe's largest structures formed

First Kuiper belt member (or Trans-Neptunian Object) discovered

Discovery of two planets orbiting a pulsar

1994 Comet Shoemaker-Levy 9 crashes into Jupiter

1995 First extrasolar planet orbiting Sun-like star (Pegasi 51) discovered

Brown dwarfs discovered

1997 Discovery that gamma-ray burst lie in distant galaxies, making them highest-energy objects in universe

1998 Announcement of evidence that expansion of universe is accelerating

1999 Chandra X-Ray Observatory deployed

First extrasolar planetary system around Sun-like star (Upsilon Andromedae) discovered

2000 Hayden Planetarium reopens (February)

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