Sunset Takes Exactly as Long as Sunrise

"The Sun moves away from you as it sets, so it should take noticeably longer to fully set than to fully rise."

Free, one clear day. Stand where you can see the horizon. With a stopwatch (your phone), time from the moment the Sun's disc FIRST touches the horizon until it is fully hidden (set). Repeat the next morning: first touch until fully up (rise). Do it for several days, and again at different times of year.

Both take the same time: about 2 minutes. The Sun's disc is 0.53° wide and the sky rotates at 15° per hour (0.25° per minute), so the disc takes 0.53 / 0.25 = 2.1 minutes to fully rise or fully set. Measured times agree - sunrise and sunset are symmetric, every day.

This is a favourite test flat Earthers run on themselves: the prediction comes from their model's own geometry (a receding light source), and the result is always the same - symmetry. MCToon documents the underlying angular-size and angular-elevation math in detail.

On a flat plane the Sun's distance changes dramatically between sunrise and sunset, so its apparent size - and the time to fully cross the horizon - should change too. It doesn't. On a globe the Sun is 150 million km away, so its distance barely changes over a day and symmetry is exactly what you'd predict.