Every Sunset You've Seen Was Already Over

The Sun you watch touch the horizon is not where it looks. It is a picture the atmosphere has lifted into view, and the moment the last sliver disappears, the actual Sun has already been completely below the horizon for a few minutes.

Air gets thinner with height, so its refractive index drops as you go up. Sunlight crossing those layers at a low angle bends gently toward the denser air below. Your eye traces the light back along its final direction, which points above the Sun's true position. On an average evening the lift at the horizon is about 34 arcminutes, a little more than the Sun's own width (about 32). Official sunset times build that in: the Sun's centre is geometrically 50 arcminutes below the horizon at the moment it "sets".

In central Europe that works out to roughly three minutes of Sun you are seeing after it has gone. Near the equator the Sun drops more steeply and it is closer to two; further north it is longer. And the 34 is an average, not a constant. Cold, dense air near the ground can make it far larger.

That is also why the September equinox, "equal night", does not deliver equal day and night. On 22 September Zurich gets 12 hours 12 minutes of daylight, not 12. The air stretches both ends of the day: refraction adds minutes at sunrise and at sunset, and the rest comes from sunrise and sunset being defined by the Sun's upper edge, not its centre.

Sources, in the order the video uses them:
Sunset is defined with a mean horizon refraction of 34 arcminutes and a solar semidiameter of 16, so the Sun's centre is geometrically 50 arcminutes below the horizon when it "sets" - US Naval Observatory: https://aa.usno.navy.mil/faq/RST_defs
The same 0.833 degrees (50 arcminutes) used for sunrise and sunset, and why errors grow away from the equator - NOAA solar calculator notes: https://gml.noaa.gov/grad/solcalc/calcdetails.html
Refraction at the horizon slightly greater than the Sun's apparent diameter - Wikipedia, "Atmospheric refraction": https://en.wikipedia.org/wiki/Atmospheric_refraction
Measured horizon refraction at sunset ranging from 0.23 to 1.68 degrees (abstract read) - Schaefer & Liller, PASP 102 (1990): https://iopscience.iop.org/article/10.1086/132705
The 2026 September equinox instant, 23 Sep 00:05 UTC - USNO: https://aa.usno.navy.mil/api/seasons?year=2026
Zurich on 22 Sep 2026: sunrise 07:12, sunset 19:24, 12 h 12 min of day - USNO one-day data: https://aa.usno.navy.mil/api/rstt/oneday?date=2026-09-22&coords=47.37,8.54&tz=2&dst=false
Why "equal night" does not mean equal day and night (background) - EarthSky: https://earthsky.org/astronomy-essentials/everything-you-need-to-know-september-equinox/
The "three minutes" is our arithmetic on the USNO definition: 34 arcminutes of descent at 10.2 degrees per hour at Zurich's latitude is about 3.3 minutes; at the equator, 15 degrees per hour gives about 2.3.