Places · Dark sky
Mont-Mégantic
The world's first International Dark Sky Reserve, created after the surrounding municipalities replaced 2,500 light fittings to protect the observatory on the summit.
- Where
- Quebec, Canada
- Coordinates
- 45.46°N 71.15°W
- Since
- 2007
- On the map
- Show me
- More
- darksky.org
The sky from here
This is a zone 3 sky — rural transition on the nine-grade scale, Bortle 3–4, reaching roughly magnitude 6.2–7.0 unaided. The Milky Way is clearly there but loses its detail near the horizon. Light domes are obvious in several directions.
That grade puts 106 of the catalogue within easy reach of 10×50 binoculars and 106 within a 130mm — 38 of them need no instrument at all. Genuinely dark sky — zone 2 or darker — starts about 7 km south.
There is no season here in which the sky fails to get properly dark — the Sun clears eighteen degrees below the horizon on all 365 nights.
The galactic centre tops out at 16° from this latitude — low enough that the busiest part of the Milky Way is always behind the most atmosphere, which is what separates this sky from a southern one. Of the 110 Messier objects, 14 never set from here and every one of them rises at some point in the year.
Of everything in the catalogue, Sunflower Galaxy, Andromeda Galaxy and Cat's Eye Galaxy are the best served here, climbing to within a few degrees of straight up — an object at the zenith is being seen through the least air it will ever be seen through, and the difference against the same object low in the south is not subtle.
Whirlpool Galaxy, Little Dumbbell and Pinwheel Galaxy never set from this latitude, so they are available on any clear night of the year rather than for one season of it.
Read at 45.46°N 71.15°W. Darkness is estimated rather than measured; everything else follows from the latitude and holds along the whole parallel. How accurate this is.
Nearby
Questions
What part of the sky never rises at Mont-Mégantic?
Everything south of declination −45°. From 45.5°N that is a cap 45° in radius centred on the south celestial pole, which is 15% of the whole celestial sphere. Nothing about the calendar or the aperture changes that — the cap is below the horizon at every hour of every night. Its mirror image, the same 15% around the north celestial pole, is circumpolar here and never goes down.
How many hours of true darkness does Mont-Mégantic get?
11 hours 42 minutes on the best night, around 21 December, falling to 3 hours 4 minutes around 21 June. The measure is astronomical darkness — the Sun a full eighteen degrees under — not simply the hours between sunset and sunrise. Every night of the year gets there eventually, which is the quiet advantage of not being any further from the equator than this.
When is the Milky Way best from Mont-Mégantic?
From roughly May to September, peaking around 17 June when the core is on the meridian at midnight and drifting into the evening sky thereafter. The useful thing about 45.5°N is that every one of those nights actually gets dark — at higher latitudes the best weeks of the core season are also the weeks with no astronomical night at all.
How far is Mont-Mégantic from the other sites on this map?
Its closest neighbour on this map is Cherry Springs State Park, 682 km away to the south-west. That is also the nearest other dark sky, with the next one 3,330 km beyond it. Distances are great-circle, so they are what a signal covers rather than what a road does.