Modern Astronomy

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Annie Jump Cannon

1901

classified thousands of stars to the OBAFGKM sequence based on spectra

Ejnar Hertzsprung & Henry Norris Russell

1911 - 1913

devised the Hertzsprung-Russell (H-R) diagram which plotted the luminosities of stars against their colors

Arthur Eddington

1924

discovered the empirical mass-luminosity relationship of a star

Jan Hendrik Oort

1927 - 1932

calculated approximate distance to center of galaxy, determined period for sun to complete one revolution of Milky Way, calculated the mass of the Milky Way, and discovered evidence of dark matter

George Gamow

1929

proposed the theory that solar energy is released through a process called nuclear fusion

Edwin Hubble

1929

Hubble's Law - proportionality between distance and speed of galaxies

Clyde Tombaugh

1930

discovered Pluto

Grote Reber

1937

became first legitimate radio astronomer after inventing the first radio telescope

George H. Herbig

1946 - 1947

discovered Herbig-Haro objects - gas clouds associated with young stars

Sir Fred Hoyle

1950

coined the term "Big Ban Theory" for a concept which he did not accept, believed in the steady-state model of the universe instead

Gerard Kuiper

1951

discovered the Kuiper belt of minor planets andcomets at the edge of the solar system (among other things)

James Van Allen

1958

discovered radiation belts around the Earth that he named Van Allen Belts

Allan Sandage

1960

discovered the first quasar

Jocelyn Bell & Antony Hewish

1967

discovered the first four pulsars, though Bell was not recognized as a recipient of the Nobel Prize in Physics

John A. Wheeler

1967

Coined the term "black hole" and introduced the concept of space foam

Charles Thomas Bolton

1971 - 1973

discovered the first black hole - known as Cygnus X-1

Stephen Hawking

1973

proved that black holes emit radiation and eventually evaporate by combining the theory of general relativity and quantum theory

William K. Hartmann

1975

proposed the most widely accepted theory of the moon's creation - debris from the Earth after a collision congealed to form the moon

James Ludlow Elliot

1977

discovered the rings of Uranus

Alan H. Guth

1978

developed the cosmic evolution theory known as the inflationary universe

James W. Christy

1978

discovered Charon - Pluto's largest satellite

Tadashi Nakajima

October 1994

led the team who discovered the first Brown Dwarf

Mike Brown

2005

work resulted in the demotion of Pluto to a dwarf planet