Our Star Attraction
The Mt. Megantic problem
A unique setting for research, technological development and higher education

The Centre de recherche en astrophysique du Québec (CRAQ) is the jewel of Canadian astronomy [mars.astro.umontreal.ca/centre]. The main apparatus of this centre is the Mt. Megantic Observatory (OMM), which is the fourth largest telescope in Canada and the largest in eastern North America.

The mission of the Observatory is to conduct astrophysical research and train young researchers for work in other major observatories around the world and thereby export expertise from the Observatory. Also, the Observatory develops state-of-the-art instruments that are globally recognized for their high quality.

A unique setting for introducing astronomy to the general public

At the foot of Mt. Megantic is an astronomical museum and educational centre known as the ASTROLab. Special installations, such as the public observatory (OPMM) and multimedia theatre, allow the public to participate in amazingly beautiful evenings. The theatre is equipped with a giant, high-resolution screen and projects the fantastic film “Rythmes cosmiques”.

The ASTROLab is situated within the Mt. Megantic provincial park and attracts over 20,000 visitors each year.

Light pollution at Mt. Megantic
Since many research, educational and tourist activities in the Mt. Megantic region rely on astronomical observations, protection of the starry sky is crucial.  Even though the mountain is located far from major urban centres, light pollution at the summit more than doubled between 1978 and 1998.  When the Observatory was first built in 1979, brightness of the night sky was 25% higher than natural values.  Given that annual increases are in the order of 5 to 10%, light pollution soon became a real threat to scientific studies and even the basic vocation of the Observatory.

In spite of constantly increasing light pollution, researchers at the Observatory work under a night sky of exceptional quality.  The photo above shows the amount of light pollution, as measured by Chad Moore (Night Sky Team, US National Park Services).  Apart from the small domes produced by the neighbouring towns (shown by the colours pink through green), one can see that the sky is mostly dark.

Sources of light pollution at Mt. Megantic

When it was agreed that something should be done about artificial brightness in the region, the breakdown by municipality was:

  • 50% from communities situated within a radius of 25 km from the Observatory;
  • 25% from the City of Sherbrooke;
  • 25% from other sources.

Despite their small size, the municipalities situated within a radius of 25 km contribute disproportionately to light pollution. This is due to the fact that illuminance decreases as a function of the square of the distance. Thus, a town of 3,000 inhabitants at a distance of 10 km pollutes the sky as much as a city of 300,000 inhabitants 100 km away. Because it is situated at a distance of 250 km from Mt. Megantic, the conglomerate of Montreal with 3,000,000 inhabitants pollutes as much as a town of 3,000 inhabitants at the foot of the mountain.

Municipalities that contribute to light pollution measured at the Observatory.