Every now and then, somebody with a lot more self-belief than is warranted will set out to the “end” of the Earth in order to “prove” we are living not on an oblate sphere, but a pancake.
They have traveled to Antarctica for a “final experiment” and attempted to sail to the edge, always ending in the disappointing realization that the Earth is round, or at least admitting that their own flat-Earth models are somewhat lacking. But they do not need to do that. As one Internet hero has recently demonstrated, you can personally prove the Earth is round without leaving it, and with some very basic equipment.
In a time-lapse purportedly shot between March 2024 and March 2025, and posted to Reddit, you can see one piece of evidence traced over the ground.
Following the corner of the garage’s shadow and marking where it is at the same time of day over the course of a year, you can see that it traces out a sort of figure of eight symbol, known as an analemma. Analemmas are created by the Earth and Sun’s relative motion, and are very well-described by usual Solar System models where the Earth – an oblate spheroid – orbits the Sun.
If the Earth were a flat surface and the Sun moved overhead and you traced shadows over the course of a year, the shadow’s tip would remain stationary. Instead, you get these figures, which require a little orbital and calendar knowledge, but are much more interesting than anything a flat-Earth model can produce.
The simple textbook answer for why they occur is that the Earth’s 23.5° tilt causes the Sun to appear higher or lower in our sky throughout the year (affecting the vertical axis) while the Sun’s elliptical orbit affects the horizontal position.
“The Sun will appear at its highest point in the sky, and highest point in the analemma, during summer. In the winter, the Sun is at its lowest point,” the Stanford Solar Center explains. “The in-between times generate the rest of the analemma pattern. Analemmas viewed from different Earth latitudes have slightly different shapes, as do analemmas created at different times of the day.”
But while the orbit and tilt of the planet play their part, this is not the only factor involved. In fact, what analemmas are measuring really is how far local time (e.g. UCT) differs from mean solar time as the Earth makes its way around the Sun.
“Introductory textbooks and other pedagogical sources sometimes explain the analemma’s horizontal displacement as resulting solely or primarily from the eccentricity of the Earth’s orbit,” a paper on the topic explains.
“This is clearly incorrect: Kepler’s second law implies that a planet’s orbital angular velocity is faster than the mean when the planet is near the perihelion and slower when it is near the aphelion. If this were the dominant factor in determining the equation of time, then the azimuth of the Sun, observed at noon, would be greater than 180◦ during half of the year and smaller than 180◦ during the other half, giving a figure-zero rather than a figure-eight for the analemma,” it continues.
“Orbital eccentricity does play an important role in determining the precise form of the equation of time, but the analemma would still be a figure-eight if the Earth’s orbit were perfectly circular.”
The reason for the figure of eight analemma is the difference between the actual position of the Sun in the sky and the mean solar time measured by your own clock.
“The apparent variation in the position of the Sun has been intensively studied by astronomers, and is well understood. It is the cause of variations in the length of a solar day and the difference between solar time and mean time,” another paper on the topic explains.
“The variations are encapsulated in an expression called the Equation of Time (the term ‘equation’ is used here in a historical sense, meaning a correction or adjustment).”
For example, 12 pm is noon every day of the year, going by our clocks. But solar noon, when the Sun is actually highest in the sky, varies throughout the year. Take a photo of the Sun at 12 pm every day, and you are mapping the difference between the time measured on your watch vs the actual position of the Sun at that point, the result of the Earth’s tilt relative to the Sun at that time of year.
On Earth, depending on where you are, the analemma can be at different angles, though it always traces out this figure-of-eight pattern. The angle of analemma at different latitudes is predicted by a spheroid Earth model, but in a flat-Earth model, you have to invoke the Sun moving along odd paths, and without regard to physical laws, in order to replicate this effect.
In some “ideas”, the Sun bobs up and down to account for the seasons, but for some reason without a corresponding size change in the sky. None of these accounts for analemmas as well as current models, nor the different analemmas seen at different altitudes.
“I’m a physics student. This is simply one more piece of evidence that agrees with our models of the solar system,” as Reddit user Haventyouheard3 added, responding to the video. “It is, however, impossible to argue against a flat earther using this because even they don’t know wtf is going on in their model.”
Source Link: Flat-Earthers Proved Wrong Using A Security Camera And A Garage