Places · Impact site
Sudbury Basin
An impact 1.85 billion years ago melted through the crust and concentrated nickel and copper into what became one of the richest mining districts in the world.
- Where
- Ontario, Canada
- Coordinates
- 46.60°N 81.18°W
- Age
- 1849 million years ago
- On the map
- Show me
- More
- nrcan.gc.ca
The sky from here
This is a zone 5 sky — suburban on the nine-grade scale, Bortle 5–6, reaching roughly magnitude 5.2–6.0 unaided. The Milky Way is invisible or nearly so. Clouds are lit from below. You can read a newspaper outside on a clear night.
That grade puts 82 of the catalogue within easy reach of 10×50 binoculars and 85 within a 130mm — 15 of them need no instrument at all. Genuinely dark sky — zone 2 or darker — starts about 30 km west.
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 centre of the galaxy only ever reaches 14° above the horizon from here, so the richest part of the Milky Way is always seen through the thickest air. It is the single biggest difference between this sky and one further south. 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 46.60°N 81.18°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 Sudbury Basin?
Everything south of declination −43°. From 46.6°N that is a cap 47° in radius centred on the south celestial pole, which is 16% of the whole celestial sphere. It is out of reach permanently rather than seasonally: no time of year and no instrument brings it above the horizon. The matching 16% around the north celestial pole is the same geometry inverted, and never sets.
How many hours of true darkness does Sudbury Basin get?
From about 2 hours 27 minutes at the thin end of the year, near 21 June, up to 11 hours 45 minutes around 21 December. That counts only proper astronomical night, with the Sun eighteen degrees down; the merely-dark hours either side of it are longer. Unlike sites further from the equator, no part of the year here is written off entirely.
When is the Milky Way best from Sudbury Basin?
Mid-June at its highest, with a workable season either side of it running from about May into September. Because 46.6°N keeps full astronomical darkness all year, the whole of that season is usable, which is not the case for observers much further from the equator, who lose the peak of it to summer twilight.
How far is Sudbury Basin from the other sites on this map?
Its closest neighbour on this map is Cherry Springs State Park, 611 km away to the south-east. The nearest other impact site is Manicouagan crater, 1,050 km to the north-east. Measured as the great circle between coordinates, which is the shortest path across the surface and rarely the one you could travel.