John Stanley Plaskett, who conceived and designed the 1.8m telescope that bears his name, was an internationally recognized scientist and a strong proponent of public science outreach. Here are a few of his achievements.

Early life

Born on an Ontario farm in 1865, J.S. Plaskett developed an early interest in mechanical engineering and astronomy. He made his own telescope and eventually joined the Edison Company as an electrical engineer.

University & Early Career

During the 1890's, Plaskett worked as a mechanician at the University of Toronto while completing an honours degree in physics. He was hired by Chief Astronomer William King to work in Ottawa's Dominion Observatory.

In his role at the new observatory, Plaskett developed the fledging Canadian Astrophysics programme, joined the International Astronomical Union's committee on binary stars, engaged the public, and developed his dream for a 'great Canadian reflecting telescope'.

"The project for a great reflecting telescope of 72 inches aperture for the Dominion... has now crystallized into definite action as the contracts for the construction of the instrument have been awarded"

While the new Dominion Astrophysical Observatory was being constructed in Victoria, Plaskett continued his work on spectrograph design and was ready to engage on an ambitious program of binary star observations on its completion.

Plaskett's Star

The first few years were productive, if routine. But in December 1921, Plaskett found an object that captured the public imagination: Plaskett's star, a pair of massive stars circling each other. Taking over 40 spectra, Plaskett estimated that the pair were 140 times the mass of the sun or more, 27,000 times brighter, and orbited each other in 14.5 days, making it the most massive star known to man.

The discovery was covered in several prominent newspapers, reinforcing the promise of the new Victoria telescope while capturing the imaginations of thousands of Canadians and Americans.

International Recognition

Just 12 years after the observatory opened, it was the world leader in binary star observations. In January 1930, Plaskett reported that "of the 900 known binaries, 400 were discovered here; of more than 300 spectroscopic binaries measured by all the observatories in the world, 106 were measured by the observatory on Little Saanich Mountain."

The Structure of the Milky Way Galaxy

Driven by the desire to understand the structure and shape of the Milky Way galaxy, J.S. Plaskett and J.A. Pearce laboured throughout the late 1920's on the study of galactic rotation. Using the efficient Victoria telescope, they discovered that the galaxy rotates once every 240 million years, and that our Solar System lies well away from the galactic centre.

To the amazement of the general public, it was found that the solar system was moving around the centre of the galaxy at high speed. This discovery was celebrated throughout the astronomical community and was widely reported in the international press, featured in the New York Times.


Plaskett was awarded the gold medal of the Royal Astronomical Society in 1930, the Flavelle Medal of the Royal Society of Canada and many other medals and honours, including a Fellowship of the Royal Society and being honoured as a Commander of the British Empire by the British Government.

Public Outreach

In addition to his scientific achievements, Plaskett was a great promoter of public engagement and the advancement of Canadian astronomy. He regularly delivered lectures and articles for interested members of the public.