Photo by Bill Longo
1907- First proposed by Clarence A. Chant
1921 - Public lecture introduces Dr. Chant to David Dunlap
1924 - David Dunlap dies at 61
1926 - Jessie Dunlap agrees to continue the observatory project
1930 - Final approval and project announcement
1933 - 74" mirror poured at Corning Glass Works
Telescope housing arrives in Canada for assembly
May 31, 1935 - Official Opening - DDO becomes world's second-largest telescope in operation
1935 - Dr. Helen Hogg joins DDO staff and begins internationally renowned research on globular star clusters; takes over 2000 images and discovers hundreds of variables stars that she discusses in over 200 publications
1951 - 15 cm Cooke refractor originally used at U of Toronto's downtown campus for the 1882 transit of Venus moved into the north dome of the DDO Administration Building. (Telescope donated to the National Science Museum in 1984.)
1953 - Dr. Don MacRae begins working for DDO and over next ten years constructs several radio telescopes at the Observatory and an 18 metre telescope in Algonquin Park
1958 - Dr. Sidney van den Bergh joins the DDO and devises a new classification system for galaxies using the Observatory's copy of the Palomar Sky Atlas; he goes on to become one of the giants in the study of galaxies
1970 - University of Toronto Southern Observatory (UTSO) begins operating at Las Campanas Observatory in Chile with instrumentation and operational support provided by the DDO. Dr. R. F. Garrison uses UTSO and DDO telescopes to establish himself as the world's foremost expert in stellar classification
1971 - Dr. Tom Bolton uses DDO 74" to confirm the existence of black holes
1995 - Town of Richmond Hill passes a landmark By-law to Regulate Light Pollution modelled after the efforts of Prof. Bolton during the preceding 25 years.
2007 - University of Toronto announces intention to close DDO in favour of Dunlap Institute
2008 - Property purchased by Metrus Development Inc, which advertises for an organization willing and able to operate the observatory and telescope
2009 - Royal Astronomical Society of Canada, Toronto Centre, puts forward a proposal to operate the Observatory and telescope for education and public outreach programs.
July 2009 - David Dunlap Observatory reopens for public viewing nights and welcomes more than 1700 visitors in its first season of operation
August 2014 - David Dunlap Observatory welcomes its 20,000th visitor since RASC Toronto Centre assumes stewardship of the facility.