On PRI’s The World today, amid stories of Muhammad Ali’s memorials, there was a little story about Ramadan, the yearly fasting. One man’s phone’s Ramadan app sounded at sundown, when they break the fast and eat. Similarly, the Jewish Sabbath starts at sundown.
Now, what if those folks lived on the 20th floor? Do they wait until the sun sets from their angle, or is the theological sunset the same as at ground level? If it’s the first, the guy’s phone would chime several minutes early. If it’s the latter, the Muslims would have a longer fast every day than their downstairs brethren, and the Jews would have a shorter Sabbath.