Jack Forster analyzes the Apple Watch Solar Face for Hodinkee and starts talking about twilight:
Twilight, as it turns out, is further divided into three phases: Civil Twilight, Nautical Twilight, and Astronomical Twilight, and it is the phases of twilight, plus sunset, which are indicated by the four dots clustered at sundown.
He continues describing every form of twilight and why it is important to be defined. One example:
Civil Twilight is not only an astronomical event – it is also important in fields as diverse as aviation and law. Here in the United States, the FAA defines night, and the additional regulations pertaining to nighttime aircraft operations, as the period between the end of Civil Twilight and the beginning of morning Civil Twilight.
Matt Yglesias explains where time zones come from and how we get rid of them.
Time is seen in a particularly different light by Eastern and Western cultures, and even within these groupings assumes quite dissimilar aspects from country to country. In the Western Hemisphere, the United States and Mexico employ time in such diametrically opposing manners that it causes intense friction between the two peoples. In Western Europe, the Swiss attitude to time bears little relation to that of neighboring Italy. Thais do not evaluate the passing of time in the same way that the Japanese do. In Britain the future stretches out in front of you. In Madagascar it flows into the back of your head from behind.
I didn’t know there were so many different understandings of time.