David Dunlap Observatory in Richmond Hill, Ontario, Canada

David Dunlap ObservatoryLocated in Richmond Hill, Ontario, Canada, the David Dunlap Observatory is one of the largest astronomical observatories in the world. Founded in 1935, the observatory was originally built to house a 74-inch telescope, the largest in Canada. Today, the observatory is home to various powerful telescopes that are used for research and public outreach. The observatory has been open to the public for special events such as stargazing nights and educational programs in recent years. The facility also includes an education center, library, and museum. The David Dunlap Observatory is a valuable resource for astronomers and amateur stargazers alike.


What is David Dunlap Observatory

The David Dunlap Observatory is an astronomical observatory located in Richmond Hill, Ontario. It is owned and operated by the University of Toronto. The telescope at the observatory is currently the largest refracting telescope globally. It has a 1.88m mirror. The telescope is used for research purposes and public outreach events such as stargazing nights. The observatory also houses a library and an exhibit hall. In addition to the telescope, the observatory has several other research instruments, including:


Spectrograph: A spectrograph is an instrument that separates incoming light by its wavelength or frequency and records the resulting spectrum in some multichannel detector, like a photographic plate.


Photometer: A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and includes the visible spectrum. Most photometers convert light into an electric current using a photoresistor, photodiode, or photomultiplier.


Reflector telescope: A reflecting telescope is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image.


The David Dunlap Observatory is open to the public for tours and events on select days.



The David Dunlap Observatory (DDO) is an astronomical site in Richmond Hill, Ontario, Canada. Established in 1935, it was owned and operated by the University of Toronto until 2008. It was then acquired by the city of Richmond Hill, which provides a combination of heritage preservation, unique recreation opportunities, and a celebration of the astronomical history of the site. Its primary instrument is a 74-inch (1.88 m) reflector telescope, at one time the second-largest telescope in the world and still the largest in Canada. Several other telescopes are also located at the site, including a small radio telescope. The scientific legacy of the David Dunlap Observatory continues in the Dunlap Institute for Astronomy & Astrophysics, a research institute at the University of Toronto established in 2008.


What did the David Dunlap Observatory discover?

A spectacular discovery was made at the David Dunlap Observatory in 1972. One of the observatory’s astronomers, Charles Thomas Bolton, discovered Cygnus X-1, the first black hole ever identified. In 1987, the observatory was responsible for another amazing discovery thanks to its telescope in Las Campanas, Chile. The telescope discovered Supernova 1987A, the closest supernova explosion to Earth in 400 years. The David Dunlap Observatory has been responsible for several other important astronomical discoveries.



The David Dunlap Observatory offers a variety of educational programs for students of all ages. These include:


Stargazing Nights: These events are open to the public and provide an opportunity to view the night sky through the observatory’s telescope.


School Programs: This program is designed to meet the Grade 3, Grade 6, Grade 9, and Grade 12 Ontario Curriculum requirements for Earth and Space, Science, and Astronomy units at those grade levels, for both academic and applied streams. Programs can also be tailored to students from other grade levels (SK to 12). We welcome students from all school boards, private schools, and homeschooling groups. Students will leave the presentation with a craft project, a Moon Gazers guide, or a Star Finder as appropriate for the age group. Visit DDO Programs to book your group.


The observatory offers summer camps for children aged 8-12. These campers will learn about astronomy and have the opportunity to view the night sky through the telescope (weather permitting).


Visit David Dunlap Observatory Today!

The David Dunlap Observatory is a great place to learn about astronomy and the night sky. It offers a variety of educational programs for people of all ages and the opportunity to view the night sky through its telescope. If you are interested in learning more about astronomy or just want to have a fun night out stargazing, check out the David Dunlap Observatory!