We start by pointing out a few readily-verifiable facts. Some additional discussion and a summary can be found at the end, in section 2.
The sun sets by crossing the horizon. This can be observed directly. The same goes for sunrise as well as sunset. The same goes for the moon and the constellations.
This is easy to observe from any location where the air is not too hazy.
Note that in a flat space, the horizontal direction is the same for everybody. That’s what “flat” means. So if something is below the horizon for one observer, it’s below the horizon for everybody.
That means it is not possible to have a flat-earth model that is consistent with the observed sunset, along with the existence of timezones and a few other simple uncontroverted facts.
Also the azimuth of the sun, moon, and constellations as they rise and set. The sun sets very nearly due west this time of year.
Observe the azimuth of the rising moon and setting moon. From late September to late March it rises and sets somewhere a bit south of due east. This is quite impossible in typical flat-earth models that put the north pole in the middle.
Also the angular size of all the above as they rise, move across the sky, and set.
Direct observation of the horizon, which is well below the horizontal when viewed from an airplane.
Glide slope service volume extends out 10 nm, sometimes more 10 nm / earth’s circumference = 0.16668 degree = 1/4 of full scale deflection = 88 feet glide-slope full-scale deflection = 0.7 dgree
Great-circle air routes in the southern hemisphere. Wildly inconsistent with the Gleason map.
The rotation of large-scale weather patterns, which go counterclockwise north of the equator and clockwise south of the equator. This is important to understand. Lives are at stake.
Consider the behavior of large-scale weather patterns. If you have a cold front extending north/south, the wind flows mainly south-to-north on the east side of the front, and north-to-south on the east side of the front.
Cyclones spin counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.
Note: A hurricane is a cyclone in the western North Atlantic or the eastern North Pacific. A typhoon is a cyclone in the Western North Pacific.
Also the rotation of a Foucault pendulum. It’s not super-easy to construct one, but there are plenty of them around.
Direct photos of the earth from space. Also live video from the space station, showing life in micro-gravity, and showing the earth.
Direct observation of satellites as they move across the sky. The space station is visible to the unaided eye on occasion from almost all the populated locations on earth. It is an easy naked-eye object, even when the sky is badly light-polluted. It is brighter than any start. It is brighter than Mars, Saturn or Jupiter.
The occasions are predicted. Hundreds upon hundreds of FB pages have posted pictures.
GPS depends on dozens of satellites in super-precisely predictable orbits.
Surveyors must routinely make corrections to account for curvature, in order to ascertain what’s level and what’s not.
The celestial south pole is directly above the geographic south pole. The circumpolar constellations have been observed by billions of people. Every flat-earth model I’ve ever seen is unable to accomodate both a north pole and a south pole. So they’re all dead on arrival.
If you believe in a flat earth, then the sun, moon, and stars cannot possibly be very high above the earth’s surface. They must be local, in order to account for the fact that they look different when viewed from different latitudes and longitudes.
The alleged height can easly be determined by triangulation. Alas, depending on details of how you perform the triangulation, you get multiple wildly inconsistent answers.
The distance to the moon has been measured using laser ranging, accurate within millimeters.
The distance to Mars, Venus, and Mercury, has been measured using radar. This in turn pins down the location of the sun. And upholds the Kepler 1-2-3 law.
Even when it is not exactly on the horizon, the sun is low in the sky, within a few degrees of the horizon, morning and evening, every day. This becomes particularly obvious when you see a cloud deck lit from below.
Similarly, the moon gets low in the sky.
There are always some stars low in the sky, north, south, east, and west.
To circumnavigate the earth along a rhumb line of constant latitude 60∘south requires traveling 12,000 miles. This is wildly inconsistent with the conformal interpretation of the Gleason map and every other flat-earth map I’ve ever seen.
Since there are yacht races that circumnavigate Antarctica, you can be pretty sure the distances are well known.
Sunrise on Mt. Fuji. Also Mt. Roland, Tasmania.
Erik Korthof This reminds me of the Alp Glow and also the Uluru (former Ayers) rock in Australia at sundown and sunset.
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