Twilight

Hamilton, New Zealand
September 2021

Momentarily, as I was ascending the elevator in my apartment building yesterday, I paused and mused, "It's probably time to write an article." I had to think of a topic - sometimes I know it right away, other times it takes a while.

Almost immediately - before I'd even passed beyond the 4th floor - the image of a beautiful sunset came to mind, and it stayed with me until, moments later, I considered that sunsets, pretty as they are, really just mark a conversion between day and night, and that perhaps the conversion itself was a more worthy topic. But what exactly describes the transition from day to night? For there is much daylight remaining after the sun sets. Moreover, the night certainly takes its time to darken the sky, it's not in any rush. 

The transition between day and night, or vice versa, is known as twilight. More precisely, twilight is the period of time that lies between astronomical dawn and sunrise, or between sunset and astronomical dusk (we'll define "astronomical" shortly) (1). More accurately, twilight is determined not by time, but by an angle, most particularly the angle of the sun relative to the horizon. When the sun reaches 18 degrees below the horizon, it is that exact angle that marks the introduction - or conclusion - of twilight.

Twilight, the transition between day and night.

Aesthetically, when the sun dips below the horizon it emanates particles of light that scatter across the sky, colliding with cerulean particles of gas, creating many beautiful colours. In fact, there is a certain period of twilight colloquially called the blue hour owing to the fact that sunlight during this time takes on a dark blue shade, which looks quite different from the usual blue of the daylight sky (and can make for great photos).

Stages Of Twilight

Twilight is divided into three stages, which are aptly named.

Civil twilight starts and ends when the sun reaches 6 degrees below the horizon. Settlers and lawmakers use civic twilight to mark when certain events transition from legal to illegal - in some countries, for example, drivers must turn their headlights on (or can turn them off) during this time period. During civil twilight, enough sunlight remains in the sky such that artificial lighting is not required. Only the brightest objects, such as Venus, the "morning (or evening) star," can be seen during civil twilight.

Nautical twilight begins and ends when the sun reaches 12 degrees below the horizon. This is the moment of wanderers. Since many stars are visible during nautical twilight, and the horizon can still be seen, sailors have often used this stretch of time to take star sightings. Relying on the remaining natural light it is possible to see outlines of objects, to understand the gist of them. But not the details.

​Astronomical twilight begins and ends when the sun reaches 18 degrees below the horizon. The time of dreamers, when greater things may become faintly visible, such as nebulae and galaxies. Without artificial lighting, it is difficult to see much of anything on the ground during astronomical twilight...perhaps this is a time best spent looking upwards, towards the cosmos. A time to learn and change what we do, readying ourselves for what is to come.

Civil twilight over a city.

Nautical twilight over the water.

Astronomical twilight over a lighthouse (2).

A 50-Year, Global Twilight

Since the 1970s, human civilization has been in the midst of a 50-year, global twilight that has influenced health, money, and many other aspects of daily life.

With respect to health, thanks to the experiment whereby healthcare systems now rely excessively on drugs over healthy lifestyle practices, amazingly, nearly 75% of people in the United States are currently overweight or obese (3), with other western countries showing similar numbers. Lifestyle-related disorders such as type 2 diabetes, heart attacks, cancer, and Alzheimer's disease have risen sharply in prevalence over the last several decades and are now the leading causes of death in western countries (4). 

With respect to finances, thanks to the experiment of fiat (paper money) and the consequential inflation, just 1 US dollar in 1970 would have been equivalent in purchasing power to just over 7 dollars today (5). Moreover, in the setting of COVID-19-related government stimulus packages and quantitative easing, the actual purchasing power of fiat is probably even less than that, and it will likely continue to spiral downwards.

Interestingly, I believe we can still apply the stages of twilight to this 50-year, global experiment. We have likely have passed the civil twilight of the 1970s and 1980s, a time when nearly everyone followed the rules, and most were well off for it. And mayhaps we have drifted by the nautical twilight of the 1990s and 2000s, when a few people began to see the outline or gist of better ways, despite the fading light - of health not as a pharmaceutical-driven enterprise that feeds the companies, of money not as a fiat-driven smokescreen that feeds the bankers (these are but two examples, there are many others). Thus, at this particular moment, it is quite possible that most of the world is in the midst of the astronomical twilight stage of the 2010s and 2020s, which would put us at 15-16 degrees below the horizon. 

Erego, if we continue to cling to the somewhat experimental, never-before-seen-in-history rules of the last 50 years, it may feel as though we are nearing dusk, that the world is falling apart, that we have arrived at the cusp of a very long night - another Dark Age.

But if we can learn to change our outlook, to embrace new (and in some ways, very old) ways of thinking about how life may be lived, maybe this global astronomical twilight will see us closer to dawn, and not as I have portrayed it here. 

​The herald of a bright new day.

​Solace.

References
(1) https://en.wikipedia.org/wiki/Twilight.
(2) https://fotografen.se/portfolio/astronomicaltwilight/.
(3) Ludwig et al. 2018. Dietary fat: From foe to friend? Science 362, 764-770.
(4) Ahmad and Anderson. 2021. The leading causes of death in the US for 2020. JAMA 325, 1829-1830.
(5) https://www.in2013dollars.com/us/inflation/1970?amount=1.