Thursday 2026-09-17

Glacier National Park

St. Mary, MT

93 Excellent night. Moon down after 10:33pm, clear skies.

Astronomical darkness 9:33pm–5:27am (7.92h) · best window 10:33pm–5:27am

Milky Way core only reaches 7.6°, low enough that haze takes most of it.

Why

Cloud	92	8% cloud, essentially clear
Moon	99	first quarter at 45%, sets 10:33pm, dark after that
Darkness	88	7h55m of astronomical darkness, 9:33pm–5:27am
Transparency	88	Dewpoint spread 10.8°C, dry and steady air