A total solar eclipse will take place on Monday, April 8, 2024. The path of total eclipse takes the form of a long and narrow corridor, just 200 kilometres wide on average but stretching over 14,700 kilometres from the Pacific to the Atlantic, via Mexico (States of Sinaloa, Nayarit, Durango and Coahuila), the continental US (from Texas to Maine), Southern and Eastern Ontario (locations bordering lakes Erie and Ontario, and along the St. Lawrence River), Southern Québec (Montréal, Montérégie, Eastern Townships, Centre-du-Québec, and Beauce), New Brunswick, Prince Edward Island, and Newfoundland. This will be the first total solar eclipse visible anywhere in Canada since February 26, 1979!
After touching the surface of the Earth at sunrise in the south Pacific Ocean, 3200 kilometres south of Honolulu, the Moon’s umbral shadow will travel eastward, gradually pitching north and going over 6,800 kilometres of water without encountering any landmass. It finally makes landfall in Mexico near the coastal city of Mazatlán (State of Sinaloa); the umbra then traverses the States of Durango and Coahuila before entering the United States. It travels successively across Texas, Oklahoma, Arkansas, Missouri, Illinois and Indiana (skimming a few bordering counties in Kentucky), and then Ohio before overflying lakes Erie and Ontario and the Niagara Peninsula, spilling over their Ontarian shores, as well as parts of Pennsylvania and Upstate New York. The Moon’s umbra continues on along the St. Lawrence Valley, reaching Southern Québec near Montréal. It touches Montérégie, the Eastern Townships, Centre-du-Québec, and Beauce, as well as northern parts of Vermont and New Hampshire before cutting across Maine. The umbra reenters Canada, traversing New Brunswick and the northwestern tip of Prince Edward Island, before crossing the Gulf of St. Lawrence and reaching Newfoundland. The path of totality then returns to the watery surface of the North Atlantic Ocean where it travels another 2,400 kilometres before finally leaving the Earth’s surface at sunset.
The total eclipse will last about 2 minutes 3 seconds at the extremities of its trajectory, on the eclipse centreline. At the point of maximum eclipse, located near the Mexican city of Torreón (State of Durango), this duration reaches a theoretical value of 4 minutes 28 seconds.
Outside the path of totality, in a vast area covering most of North America (except for a small part of Yukon and most of Alaska), Central America, and the Caribbean, as well as Greenland and Iceland, we’ll be able to observe a partial eclipse of the Sun. In Canada, the eclipse generally unfolds between the late morning hours in the West, and late afternoon in the East. The exact times of the eclipse, its duration and maximum coverage of the Sun by the Moon, depend on the specific geographical coordinates and elevation above sea level at the observer’s location. Broadly speaking, the partial eclipse will be deeper in locations closer to the path of totality.
Near the limits of the path of totality
The situation becomes more complicated in the areas close to the north or south limits of the path of totality. That’s because the Moon is not a perfectly smooth sphere: the presence of asperities such as mountains, crevices and valleys along the lunar limb (i.e. the edge of the Moon’s visible disc) allow light from the Sun's bright photosphere to seep through and be visible even inside the theoretical zone of totality. Another way to consider this is that the north and south limits of the path of totality as traced out on maps are not exactly defined and sharp edged: There remains a “zone of uncertainty” of sorts, just a few hundred metres wide, where the eclipse is possibly or even probably “not completely total.”
It is therefore a good idea to seek a viewing location situated deep enough inside the path of totality, at least a couple of kilometres, to ensure that the eclipse will indeed be total and that its duration will be longer than just a few seconds. The first few kilometres are where the most significant gains in terms of eclipse duration are realised—it’s not necessary to get to the centreline of the eclipse: all that’s needed is to be well inside the path of totality, with some safety margin.
The total solar eclipse on April 8, 2024, will be problematic in this respect, because many cities and important urban areas straddle the northern or southern limits of the path of totality. In southern Québec, the northern limit of the path of totality cuts through the island of Montréal from west to east. Based on data from the 2021 Census of Canada, we estimate that 45 % of the population in the Montréal census metropolitan area (CMA, almost matching the Montreal Metropolitan Community) lives outside the path of totality (1.937 million out of 4.292 million); they are essentially the citizens of Laval and the North Shore of Montréal, as well as dwellers in the East End of the island of Montréal.
In the Centre-du-Québec region, Drummondville and Victoriaville also straddle the northern limit of total eclipse, with some sectors inside the path of totality and others just outside.
In Ontario, the Golden Horseshoe area, with its core population of about 8 million, is also bisected by the northern limit of total eclipse: the City of Hamilton and the Regional Municipality of Niagara are almost completely inside the path of totality, while Toronto and the Regional Municipalities of Peel (Mississauga, Brampton, etc.) and Durham (Oshawa, Pickering, etc.) are in the zone of partial eclipse. Parts of Halton Region (Burlington, Oakville) located closest to Lake Ontario are just inside the path of totality.
The situation in Montréal
The local circumstances of the total eclipse (its duration and timing for instance) vary enormously from one place to another on the island of Montréal. In general, totality lasts longer as one moves away from the north limit towards the centreline of the eclipse. Going deeper inside the path of total eclipse, the duration of totality increases rapidly at first, and then more slowly.
Keep in mind that to fully appreciate the awe-inspiring power of the total eclipse, one MUST BE INSIDE the path of totality. Even just outside, the Sun will not be completely hidden by the Moon, and the day-turns-to-night phenomenon will not happen. A 99.99 % partial eclipse is not in any way equivalent to “99.99 % of the experience” of a total eclipse of the Sun: the magic of totality will still be missing!
Refer to our table giving the local circumstances of the eclipse for dozens of locations across Quebec and Canada.