By Dan Hicks

Op-Ed Commentary

Like an hourglass of time, an analog astronomical almanac chart for our AD 2024 year depicts the ever-diminishing darkness of true night bounded by blue astronomical twilight, vanishing entirely in the final days of spring, then steadily returning with the summer to again reclaim its plutonian prominence by late autumn.

Officially, the hourglass is the American Astronomical Society’s (AAS) “Skygazer’s Almanac 2024 for Latitudes near 500 North” (images above and below) – intended for “the United Kingdom, northern Europe, Canada, and Russia,”at the comparative southerly Canadian latitude of 49.50 north – Cranbrook clearly qualifies.

As we all know, in Mother Nature’s natural realm, true darkness overtakes the land when our sun has settled 180 below our horizon and ends when our predawn sun ascends above that point. The slanted parallel lines denote when, in Local Mean Time (LMT), the specified celestial objects transit due south at their greatest altitude in the sky.

For example, on February 25, the famous Orion Nebula star nursery (M42) is shown as transiting at 19:15 LMT (evening 7:15), to which a 44-minute Mountain Time Zone (MTZ) civil time correction must be added, giving a rounded transit time of 20:00 MST; the correction is necessary because, ridiculously, our MTZ’s central meridian of 1050 west longitude (central SK) lies 110 east of Cranbrook’s 1160 west longitude (Calgary’s lesser correction = +36 min).

Images submitted

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