This is how the night started, on Sunday evening, September 4 — as clear a night as you could ask for in the mountains. A quarter Moon hangs over the peaks of the Continental Divide, with alpen glow, the last rays of the Sun, illuminating the mountains around Saskatchewan River Crossing, in Banff.

The North Saskatchewan River flows east out of the mountains here, after being joined by the Mistaya and Howse rivers. It was here, in the early 1800s, that David Thompson and his party of fur traders from the North West Company entered the Rockies and heading up over Howse Pass off frame to the right, to trade with the Kootenays in the interior of what is now British Columbia.

This is David Thompson country, named for one of the world’s greatest geographers and mapmakers. He mapped most of western Canada and down into the Oregon Territory. All using compasses, sextants, a Dolland refractor telescope (to observe the moons of Jupiter for telling time), and his skills as an astronomer. The Kootenays called him Koo-Koo-Sint — the man who watches the stars.

It was also here, on these open river plains, that James Hector, mapping southern Alberta with the Palliser Expedition, observed Comet Donati in September 1858.

This is a place in the Rockies with many ties to history and to astronomy.

— Alan, September 5, 2011 / Image © 2011 Alan Dyer