[walrus01]

I mean, very roughly, our western calendar based on solar observations is consistent in that the same months will always be in the same season. You can always expect that January and December will be cold, and in the northern hemisphere have some of the shortest days of the year.

The Arabic Islamic calendar is not like that. Ramadan is one of the standard months of the lunar calendar and depending on what year you're talking about, Ramadan might be exactly in the middle of summer, or it might be in the direct middle of winter. Very approximately it goes "backwards" in seasons 10 or 11 days per year and eventually wraps all the way around from the POV of the western solar calendar.

In the western calendar, the winter solstice will always fall on December 20th or 21st even going up to the year 2100. And the same for the summer solstice on June 20th or 21st.

https://www.astropixels.com/ephemeris/soleq2001.html

[AStonesThrow]

Yes but you said that "sunrise and sunset are solar reckoning" and I wasn't taking issue with the topic of lunar/solar calendars because calendars don't count off or delineate the hours in a day.

Every calendar that I'm aware of considers "days" as an abstract unit which consists of one planetary rotation, without nuances of activity or visibility of external bodies, right? True?

[walrus01]

What I meant was that for an observant Muslim, the month start and month end date of Ramadan is set by the moon, but also each day has a very slight different sunrise time and Iftar time (sunset, when you can eat and drink again) which is dependent on the sun's position.

You are right that the human perceived calendar date is something we invented rather arbitrarily. Of course, the longest day of the year was occurring on June 20th before humans invented agriculture or cities. That we call it "June" and "20" is a cultural artifact.

[AStonesThrow]

> dependent on the sun's position

Check your geocentrism

The Sun’s relative, apparent position.

Sunrise and sunset are wholly dependent on the observer’s position because “night” is a cultural construct referring to being within the Earth’s shadow rather than a dragon devouring the Sun, yes?