The Algonquin Radio Observatory was inaugurated in 1959 at Traverse Lake in the Algonquin National Park in Ontario. It was created by the National Research Council of Canada for Canadian radio astronomers who needed a site in Ontario where radio interference would be minimal.

The first director was Arthur Edwin Covington, Canada’s first radio astronomer.

More than a decade earlier, in 1946, Covington had collected data on the Sun’s radio flux (the variations in its energy output at radio wavelengths) from a site in Ottawa, and again in 1947 from Goth Hill south of Ottawa. His work became of paramount importance when he demonstrated that the intensity of solar radiation was related to the Sun’s magnetic activity, which had (and still has) crucial implications for numerous human activities, such as communications systems and power lines.

The Traverse Lake site in Algonquin National Park was selected for the Algonquin Radio Observatory due to its relative isolation from manmade interference. Covington installed a parabolic mirror with a diameter of 1.83 metres in 1960 and began moving his equipment from Goth Hill in 1962. The radio t Read More
The Algonquin Radio Observatory was inaugurated in 1959 at Traverse Lake in the Algonquin National Park in Ontario. It was created by the National Research Council of Canada for Canadian radio astronomers who needed a site in Ontario where radio interference would be minimal.

The first director was Arthur Edwin Covington, Canada’s first radio astronomer.

More than a decade earlier, in 1946, Covington had collected data on the Sun’s radio flux (the variations in its energy output at radio wavelengths) from a site in Ottawa, and again in 1947 from Goth Hill south of Ottawa. His work became of paramount importance when he demonstrated that the intensity of solar radiation was related to the Sun’s magnetic activity, which had (and still has) crucial implications for numerous human activities, such as communications systems and power lines.

The Traverse Lake site in Algonquin National Park was selected for the Algonquin Radio Observatory due to its relative isolation from manmade interference. Covington installed a parabolic mirror with a diameter of 1.83 metres in 1960 and began moving his equipment from Goth Hill in 1962. The radio telescopes operated continuously at a wavelength of 10.7 centimetres, which is an ideal wavelength for monitoring solar activity due to the Sun’s particular chemical composition.Antenna used to collect solar flux data.

In 1966, an array consisting of 32 parabolic antennas, each 3 metres in diameter, was added to the observatory. The goal was to refine the measurements from other radio telescopes by scanning the Sun’s surface every noon at a wavelength of 10.7 centimetres.

Covington had begun the construction of a giant parabolic antenna measuring 46 metres across back in 1959, and it was finally completed in 1966 as one of the largest and most sensitive radio telescopes in the world. Operating at a wavelength of 2 centimetres, it was used to study galactic and extragalactic objects that emit radio waves, such as quasars.

In 1968, the 46-metre radio telescope was used in conjunction with the 26-metre instrument at the Dominion Radio Astrophysical Observatory of Penticton, British Columbia, to simulate the resolution of a giant 3,074-kilometre radio telescope (the physical distance separating the two instruments). It was the first successful long distance interferometry experiment ever conducted.

The goal of the experiment was to discern a source of radio waves with great precision. Very large antennas are necessary to precisely determine the position of radio sources because radio waves have much larger wavelengths than visible light waves, and because the detection of any object in space depends largely on the size of the observation instrument (that is, its lenses, mirrors or radio antennas).

CovingtonThe 1970’s marked a time of increased collaboration between the Algonquin Observatory radio astronomers and the researchers at the Herzberg Institute of Astrophysics. Many new complex chemical compounds were identified for the first time in interstellar gas clouds thanks to the collaborative effort.

After planning to resurface the 46-metre radio telescope so that it could operate at wavelengths as small as 3 millimetres, the National Research Council of Canada decided instead to close the Algonquin Observatory in 1987 and purchase a 25% share in the new James-Clerk-Maxwell Observatory, which would include a radio telescope that could operate at 0.3 to 2 millimetres.

In 1990, the work of collecting data on the Sun?s radio flux moved to the Dominion Radio Astrophysical Observatory in Penticton, British Columbia. Despite lowered budgets, the antenna remained active as part of a continental network of antennas that precisely measures movements of the North American tectonic plate. Since 2008, the observatory has been operated by Thoth Technology who provide geodetic and deep space network services utilizing the 46 m antenna. The site is also accessible for education and outdoor activites.

© 2006 An original idea and a realization of the ASTROLab of Mont-Mégantic National Park

Colour photo of the Algonquin Radio Observatory

The Algonquin Radio Observatory.

National Research Council of Canada

© National Research Council of Canada


Colour photo of the antenna used to collect solar flux data

Antenna used to collect solar flux data.

National Research Council of Canada

© National Research Council of Canada


Black and white photo of Covington and one of his Radio Astronomical Antenna

Covington and one of his radio astronomical antenna.

Portrait of Arthur E. Covington held in the Riche-Covington Collection
W.D. Jordan Special Collections and Music Library/Queen's University at Kingston

© Queen's University at Kingston


The Sudbury Neutrino Observatory began operating in 1999 at a depth of 2,070 metres below the surface in the Creighton mine near Sudbury, Ontario. The goal of the observatory is to detect and study neutrinos emitted by the Sun and other celestial objects. It is the product of a collaborative effort between Canada, the United States, and the United Kingdom.

Neutrinos are small elementary particles that are electrically neutral (that is, they have no electrical charge). They interact very little with matter. So little, in fact, that matter is virtually transparent to them, and therein lies the difficulty in detecting neutrinos.

Stars produce large amounts of neutrinos. The Sun, for example, emits 200 trillion trillion trillion neutrinos each second. Billions of neutrinos pass through the Sun, the Earth and your body every instant without being hindered. In fact, during your entire lifetime, only one or two neutrinos will ever come into contact with one of the atoms in your body.

One of the major unresolved problems about our Sun is related to its production of neutrinos. In the early 1980’s, it was realized that the number of solar neutrinos de Read More
The Sudbury Neutrino Observatory began operating in 1999 at a depth of 2,070 metres below the surface in the Creighton mine near Sudbury, Ontario. The goal of the observatory is to detect and study neutrinos emitted by the Sun and other celestial objects. It is the product of a collaborative effort between Canada, the United States, and the United Kingdom.

Neutrinos are small elementary particles that are electrically neutral (that is, they have no electrical charge). They interact very little with matter. So little, in fact, that matter is virtually transparent to them, and therein lies the difficulty in detecting neutrinos.

Stars produce large amounts of neutrinos. The Sun, for example, emits 200 trillion trillion trillion neutrinos each second. Billions of neutrinos pass through the Sun, the Earth and your body every instant without being hindered. In fact, during your entire lifetime, only one or two neutrinos will ever come into contact with one of the atoms in your body.

One of the major unresolved problems about our Sun is related to its production of neutrinos. In the early 1980’s, it was realized that the number of solar neutrinos detected by various laboratories were less than predicted by theoretical calculations.

Two hypotheses were proposed: either that our knowledge of the Sun is insufficient, or that some of the neutrinos change their form during their voyage to the Earth (this phenomenon is known to affect other elementary particles), which would mean that the number of neutrinos reaching Earth is less than the amount originally emitted by the Sun.

Diagram of the Sudbury Neutrino Observatory.In 1983, Canadian researchers proposed the construction of an underground neutrino detector in an Ontario nickel mine belonging to the company Inco. The underground site would shield the detector from microwaves in the background cosmic radiation, which would normally impede the detection of solar neutrinos.

One year later, in 1984, an American researcher published a study that demonstrated the advantages of using heavy water (water in which the hydrogen atoms each have an extra neutron) as a neutrino detector. Since Canada has an abundant reserve of heavy water, it was decided that the facility would operate as a heavy water detector. The United States joined the project, follow by the United Kingdom in 1989.

Work began in 1990 and was completed in 1999. The detector consists of 1,000 tonnes of ultra pure heavy water enclosed in a transparent plastic vessel measuring 12 metres across. The vessel is itself enclosed in 7,000 tonnes of ultra pure normal water, lodged in an immense cavity measuring 22 metres wide and 34 metres high (the equivalent of a 10-storey building). It is the largest underground opening ever excavated at two kilometres depth.

The acrylic vessel is surrounded by a 17-metre geodesic dome equipped with 9,600 detectors that sense the presence of neutrinos. The frequency of neutrino detection is one per hour.

The results from the Sudbury Neutrino Observatory have demonstrated that neutrinos do indeed change their form during their trip from the Sun to the Earth, thus putting an end to the debate.

© ASTROLab/Mont-Mégantic National Park

Colour photo of the Sudbury Neutrino Observatory underground

Sudbury Neutrino Observatory.

Sudbury Neutrino Observatory

© Sudbury Neutrino Observatory


Colour diagram of a cross section of the Sudbury Neutrino Observatory

Diagram of the Sudbury Neutrino Observatory.

Sudbury Neutrino Observatory

© Sudbury Neutrino Observatory


Learning Objectives

The learner will:
  • identify recent contributions, including Canada’s, to the development of space exploration technologies;
  • describe in detail the function of Canadian technologies involved in exploration of space;
  • draw a solar system with all its components;
  • establish the link between atoms and light using different instruments.

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