Timeline | American Astronomical Society

AAS Quasquicentennial: 1899 – 2024

In celebration of its 125th anniversary, the AAS has created a timeline highlighting the breathtaking and ever-expanding discoveries and creativity of our community as we continue to seek to enhance and share humanity’s scientific understanding of the universe as a diverse and inclusive astronomical community.

Explore our interactive timeline celebrating the history of the AAS and the remarkable astronomical discoveries over the last 125 years. You can view specific events by hovering over the year, the dot, or the text box. A PDF version can be downloaded here.

AAS key activities

Scientific events and discoveries

AAS Awards and Prizes

Scientists and Nobel Prize winners

1897

First conference of astronomers and astrophysicists at the dedication of the Yerkes Observatory, hosted by George Ellery Hale

1899

The Society, initially named the "Astronomical and Astrophysical Society of America," is created at the third conference of astronomers and astrophysicists held at Yerkes

1910

Williamina Fleming publishes her discovery of white dwarf stars

1912

Victor Hess and others detect cosmic rays

Henrietta Swan Leavitt discovers the period–luminosity relation for Cepheid variables, enabling the measurement of large distances in the universe

1914

The Society is renamed the "American Astronomical Society"

1915

Albert Einstein publishes his general theory of relativity

First meeting on the Pacific Coast is held in the San Francisco Bay Area

1916

Karl Schwarzschild shows mathematically that black holes may exist

1919

Astronomers use a total solar eclipse to demonstrate predictions from Einstein's general theory of relativity

The International Astronomical Union (IAU) is formed in Belgium

1923

Edwin Hubble discovers a Cepheid variable star in the "Andromeda Nebula" and proves the existence of galaxies beyond our own

1927

Georges Lemaitre suggests that the cosmos is expanding

1929

Edwin Hubble finds the cosmos is expanding

1930

Clyde Tombaugh discovers the dwarf planet Pluto

The Society begins to sponsor topical sessions

1932

Karl Jansky detects the first radio waves coming from space

1933

Fritz Zwicky suggests dark matter may exist

1934

The first AAS prize to be endowed, the Annie Jump Cannon Award, is presented to Cecilia Payne-Gaposchkin

1940

The Society holds its most popular prewar meeting — 147 people attend and 56 papers are presented

1941

The Sky and The Telescope merge to become Sky & Telescope magazine

The Astronomical Journal becomes a publication of the AAS

1946

First Henry Norris Russell Lectureship is awarded to Henry Norris Russell

1954

First award of the Helen B. Warner Prize is given to Aden B. Meinel

1956

First parallel sessions are held in Berkeley, California, at AAS 95

1958

NASA is established via the National Aeronautics and Space Act

1960

Junior and Associate membership categories are established

First AAS meeting in Mexico

Growth rate of the Society increases from 4% to 20% per year. Membership passes the 1,000 mark and reaches 2,000 in 1968

1963

Maarten Schmidt measures the spectra of quasars, establishing that quasars are active galaxies and are among the most distant objects in the universe

1965

Arno Penzias and Robert Wilson discover the cosmic microwave background, the remnant of the very hot radiation from the Big Bang that created the universe more than 13 billion years ago

1967

The Society hosts its first meeting that features three simultaneous sessions

1968

The Division for Planetary Sciences (DPS) is formed

The Society receives three petitions to organize into divisions — high-energy astrophysics, solar physics, and planetary science

1969

Apollo 11 lands on the Moon

The High Energy Astrophysics Division (HEAD) is founded

1970

Vera Rubin and Kent Ford publish the rotation curve of Messier 31, which indicates the presence of dark matter

First meeting of the Division on Dynamical Astronomy (DDA) with the AAS

First meeting of the Solar Physics Division (SPD)

First HEAD meeting is held jointly with the Division of Cosmic Physics of the American Physical Society

Uhuru, the first satellite dedicated to X-ray astronomy, is launched from Kenya

Society meetings begin to include poster sessions

1972

The AAS assumes ownership of The Astrophysical Journal

1973

Working Group on the Status of Women in Astronomy reports that the fraction of women members is the lowest (8%) in the history of the Society

1974

First Newton Lacy Pierce Prize is awarded to Edwin J. Kellogg

1976

The Viking program lands the first two spacecraft on Mars

1977

Voyager 1 and 2 space probes are launched to study our outer solar system and beyond

1978

The first George Ellery Hale Prize is given to Eugene Parker

The first Dirk Brouwer Award is given to Victor Szebehely

1979

AAS Executive Office moves to Washington, DC;

Peter Boyce becomes the Executive Officer;

Membership reaches 3,500;

The Society's annual budget approaches $2 million;

Standing Committee on the Status of Women in Astronomy is established (the present CSWA)

AAS Executive Office moves to Washington, DC;

Peter Boyce becomes the Executive Officer;

Membership reaches 3,500;

The Society's annual budget approaches $2 million;

Standing Committee on the Status of Women in Astronomy is established (the present CSWA)

1980

First Dannie Heineman Prize is awarded to Joseph H. Taylor, Jr.

650 people attend the annual meeting in San Francisco;

The creation of the Historical Astronomy Division (HAD) is approved

650 people attend the annual meeting in San Francisco;

The creation of the Historical Astronomy Division (HAD) is approved

1981

First HAD meeting is held in Albuquerque

1983

The first infrared astronomy satellite, IRAS, is launched

1984

First Gerard Kuiper Prize is awarded to Eugene M. Shoemaker

First Harold C. Urey Prize is given to David J. Stevenson

1985

First HEAD Rossi Prize is awarded to William R. Forman and Christine Jones for their pioneering work on X-ray emission from early-type galaxies

1986

Comet Halley passes through perihelion

First Beatrice Tinsley Prize is given to S. Jocelyn Bell Burnell

1989

The Galileo mission to Jupiter launches. It reaches Jupiter in 1995

1990

The Hubble Space Telescope, the first large space-based optical telescope and the first of the "Great Observatories," is launched

1991

HAD assumes responsibility for publishing obituaries of AAS members in the Bulletin of the American Astronomical Society (BAAS)

The Compton Gamma Ray Observatory, the second "Great Observatory," is launched

1992

The Cosmic Background Explorer satellite produces a detailed map of the background radiation remaining from the Big Bang

1993

The Keck I Telescope begins science operations

1994

First HEAD Divisional Meeting is held in November in Napa, California

1995

The AAS launches the electronic Astrophysical Journal Letters, one of the first journals to offer an electronic edition. All other AAS journals appear online by 1998

The first exoplanet around a Sun-like star, 51 Pegasi b, is discovered by Michel Mayor and Didier Queloz

1997

The Cassini-Huygens mission to Saturn launches and reaches Saturn in 2004

1998

Astronomers discover dark energy

2,200 people attend the annual meeting in Washington, DC, including 200 members of the media. AAS membership totals 6,500, including 1,386 women (21%)

First LeRoy E. Doggett Prize is awarded to Curtis A. Wilson

1999

The Chandra X-ray Observatory, the third "Great Observatory," is launched

The Society celebrates its 100th anniversary with the AAS Centennial Meeting in Chicago

2002

Riccardo Giacconi is awarded the Nobel Prize in Physics for his work on X-ray astronomy

2003

The Spitzer Space Telescope, the fourth and final of the original "Great Observatories," is launched

2006

The 2006 Nobel Prize in Physics goes to George Smoot and John Mather for leading the COBE satellite (when initial results from the spacecraft were presented at the AAS meeting on 13 January 1990, the attendees gave a standing ovation)

IAU adopts a new definition of planet, resulting in the redefinition of Pluto as a dwarf planet

2007

AAS journals move to IOP Publishing and the resulting ~$2M/year savings are used to reduce subscription rates and author charges

John Bahcall Public Policy Fellowship is established, with 10 fellows serving since 2007

2009

The AAS celebrates the International Year of Astronomy in the US through a large grant ($1M) from the NSF

2010

In collaboration with ADS and other publishers in the field of astronomy, the AAS creates and takes over stewardship of the Unified Astronomy Thesaurus

2011

Space Shuttle program ends

Saul Perlmutter, Brian Schmidt, and Adam Reiss are awarded the Nobel Prize in Physics for the discovery of the accelerating expansion of the universe (papers from the two teams appeared in AAS journals)

First Donald E. Osterbrock Book Prize for Historical Astronomy is awarded to Nathan Sivin

2012

The Laboratory Astrophysics Division (LAD) is created at AAS 220

2013

AAS creates the Astronomy Image Explorer

The DDA holds its annual meeting in Paraty, Brazil, and becomes the first AAS Division to hold a meeting in South America

2015

New Horizons spacecraft flies past Pluto

AAS becomes the initial steward of Microsoft's WorldWide Telescope

AAS establishes an eBooks program with IOP Publishing (first titles published in 2017)

AAS launches AAS Nova

AAS hosts the IAU General Assembly in Honolulu, Hawai'i (last held in the US in 1985)

AAS journals go fully digital, phasing out all printed editions

First detection of gravitational waves by LIGO

The first Triennial Earth-Sun Summit (TESS) meeting, a joint meeting of the AAS/SPD and AGU/SPA, is held in Indianapolis

2017

The Great American Solar Eclipse occurs

AAS launches Research Notes of the AAS

First detection of a gravitational wave event (GW170817) that was observed to have a simultaneous electromagnetic signal

2019

AAS reestablishes BAAS as an electronic journal as a service to the community

AAS establishes The Planetary Science Journal in partnership with DPS

AAS finishes a brand redefinition and soft launches at the January meeting in Seattle

AAS acquires Sky & Telescope

The Nobel Prize in Physics goes to James Peebles for theoretical cosmology work, and to Michael Mayor and Didier Queloz for the first discovery of an exoplanet orbiting a solar-type star

HEAD celebrates its 50th anniversary

Event Horizon Telescope Collaboration releases the first resolved image of a black hole

2020

The 50th anniversary of SPD

Andrea Ghez, Reinhard Genzel, and Roger Penrose share the Nobel Prize in Physics for their study of black holes

2021

JWST launches

The Perseverance rover and Ingenuity helicopter arrive at Mars and begin sending back data

Sky & Telescope celebrates its 80th anniversary

AAS acquires Willmann-Bell books

2022

AAS journals become fully open access

First JWST images released to the public

2023

Evidence is found for the long-predicted nanohertz gravitational-wave background

2024

Dara Norman is elected as 50th AAS president and becomes the first African-American president in the Society's history

The Astronomical Journal celebrates its 175th anniversary