Brief History of Astronomy

Astronomy of the 20th Century

1900

Chaberlin and Moulton propose the new theory of the Solar System origin.

1901

Appearance of Nova Persei.

1905

The foundation of Mount Wilson Observatory established exclusively for the study of the sun. Later also used to research stars, nebulas, and galaxies.

1905

Einstein proposes the basis of the special Theory of Relativity, first described in his paper On the Electrodynamics of Moving Bodies. The theory is based on two principles:

the principle of relativity, that physical laws are the same in all inertial reference systems,
the principle of the invariance of the speed of light, that the speed of light in a vacuum is a universal constant.

1908

Hertzsprung describes giant and dwarf stars.

Leavitt discovers the relationship period - absolute magnitude for Cepheids.

60-inch reflector erected at Mount Wilson.

1911-14

Hertzsprung and Russell discover the relationship between the star spectral type and star absolute magnitude (diagram H-R).

1914

Goddard begins practical experiments with rockets.

1915

Adams discovers White Dwarfs (Sirius B).

1916

Eddington proposes the first premises of the theory of intrinsic star structure.

Einstein proposes his general Theory of Relativity, where he describes the interactions of bodies (gravitational forces) on explained as the influence of bodies on the geometry of space-time.

1917

Completion of the 100-inch Hooker reflector at Mount Wilson.

1918

Shapley provides the first model of the Galaxy structure.

1918-24

Cannon publishes the fundamental catalogue star spectra.

1919

Barnard publishes the catalogue of dark nebulas.

1920

Slipher announces th discovery of Red Shifts in the spectra of galaxies.

The first direct measurement of star diameter using interpherometer.

1923

Hubble proves that the galaxies lie beyond the Milky Way.

1926

Goddard fires the first liquid fuel rocket.

1927

Oort proves that the center of the galaxy lies in the direction of the Sagittarius.

1929

Edwin Powell Hubble discovers linear relationships between the galaxy distance and its radial velocity, demonstrated by the shift of spectral lines toward red. This indicates that galaxies move away from each other.

1930

Tombaugh discovers Pluto based on Lowell's predictions.

1931

Jansky discovers cosmic radio waves.

1937

Reber constructs the first radio telescope.

1937-40

Gamow proposes the first theory of stellar evolution.

1942

Strand speculates that 61 Cygni is attended by a planet.

1944

Van de Hulst suggests that interstellar hydrogen must emit radio waves at 21.1 cm.

1946

Bay obtains the first radar images of the Moon.

1947

Ambarcumian discovers star associations.

1949

The completion of the Hale 200-inch reflector at Mount Palomar.

1951

Ewen and Purcell discover the 21.1 cm hydrogen radio waves predicted by van de Hulst.

1951-54

Determination of the spiral structure of our galaxy.

1955

Completion of the 250-foot radio telescope at Jodrell Bank.

1957 (October 4)

The first artificial satellite launched by the Russians.

1958

The first American satellite launched.

1959

The Russian Luniks satellites: Lunik I passes the Moon; Lunik II lands on the M

Radio-location of the Sun.

1961 (April 12)

The first man (Russian astronaut - Y. Gargarin) in space.

1962

First American orbital flight by John Glenn.

Planetary probes: Mars I (Russia) and Mariner II (USA)

Discovery of the first galactic source of X-ray radiation (Sco X-1).

1963

Van de Kamp reports a planet associated with Bernard's Star.

Discovery of the first quasar (3C 273).

1964

Close range pictures of the Moon from Ranger VII (USA).

1965

Penzias and Wilson discover cosmic fossil radiation, providing direct evidence of the Big Bang Theory.

1966

First soft landing on the Moon (Luna 9 - Russia and Surveyor I - USA).

Russian probe lands on Venus.

1967

Discovery of pulsar.

1968

First manned flight around the Moon (Apollo 8: Borman, Lovell, and Anders).

1969 (July 20-21)

First man of the Moon (Apollo 11: Armstrong and Aldrin).

1970

Satellite Uhuru scans the sky in the X-ray range.

First successful soft landing on Venus (Venera 7 - Russia).

1971

Final testing of 236-inch Soviet reflector.

First probes in orbit around Mars and first soft landing on Mars (Mars 3 - Russia).

First manned mechanical vehicle on the Moon (Apollo 15 - USA).

1972

Satellite Copernicus conducts spectroscopic ultraviolet observations of stars and interstellar matter with high resolution.

The first observations in gamma radiation range.

Launch of Pioneer 10 - the first probe to Jupiter (USA).

1973

First images of Jupiter transmitted from the close vicinity by Pioneer 10 (USA).

1974

First image of Mercury's surface transmitted by Mariner 10 (USA).

1975

Completion of the 6-meter telescope in Zielenczukskaja (USSR).

1976

Soft landing of Viking space probes on Mars (USA).

1977

Discovery of Uranus rings.

1978

Discovery of Pluto's moon.

New data on celestrial objects collected by satellite Einstein (X-ray).

1980

First images of Saturn and its rings transmitted from close vicinity by space probe Voyager 1 (USA).

1983

Satellite IRAS scans the sky in infrared radiation.

1986 (January 24)

Voyager 2 approaches the planet Urananus.

(January 28) Space Shuttle Challenger disaster: 73 seconds after take-off from the Kennedy Space Center. The explosion occurred due to the failure of an "O-ring".

(March) Space probes Vega 1, Vega 2, and Giotto pass near Halley's Comet.