An 11,000 square kilometer observatory
On March 26, 2011, the Royal Astronomical Society of Canada designated Jasper National Park a Dark-Sky Preserve. At 11,228 square kilometers, it is the world's second-largest such preserve and the largest that is readily accessible, as it contains a town within its borders. The designation required a formal focus on protecting the night sky by eliminating unnecessary artificial light and educating the public about the effects of light pollution.
The darkness of a location is measured by astronomers in magnitudes per square arcsecond. In the core areas of the Jasper preserve, the sky quality reaches levels darker than 21.7 mag/arcsec², with an overall average of 21.4 mag/arcsec². This level of darkness, close to that of a sky with no light pollution at all, allows for exceptional viewing of celestial objects. It means the sky itself has a natural, faint glow from atmospheric and cosmic sources, but human-generated light is almost entirely absent. To maintain this standard, all new exterior lighting within the park must comply with strict dark-sky regulations, which specify shielding and direction.