Star trails

Star trails taken from Australia clearly showing the location of the south celestial pole

Two celestial poles are perfectly explained by a globe Earth

Star trails refers to the phenomenon where the Earth's rotation causes stars to streak in long-exposure photography of the night sky. Star trails are strong evidence against flat Earth as they very clearly show diurnal motion around two celestial poles; something which cannot exist in any flat Earth model.

Flerfs generally agree that there is a point of rotation in the northern sky near Polaris, but many are reluctant to accept the same for the south; a southern point of rotation near Sigma Octantis, as this would radically violate the Rowbothamist model which places the south pole as a ring encompassing the Earth.

The south celestial pole (SCP) does not move, yet any observer in the southern hemisphere can see it due south. On the Gleason map, this would require observers at different longitudes to be looking in totally different directions while seeing the same thing. Flerfs that don't outright dismiss the existence of the SCP tend to explain away its incompatibility with flat Earth using some combination of "refraction" and "perspective", which usually involves bringing up the "personal dome" concept.

Eric Dubay's "proof" 150

Dubay's disastrous misunderstanding of the "globe theory". Source: 200 Proofs Earth is Not a Spinning Ball (2024 Remastered Edition) at timestamp 1:41:38

Proof 150 taken from Dubay's book

Eric Dubay's proof number 150 shows how flerfs ignore the obvious problems with star trails on a flat Earth, and instead straw man the globe.

If Earth were a spinning ball revolving around the Sun it would actually be impossible for star-trail photos to show perfect circles even at the North Pole! Since the Earth is also allegedly moving 67,000mph around the Sun, the Sun moving 500,000mph around the Milky Way, and the entire galaxy going 670,000,000mph, these four contradictory motions would make star-trail time-lapses all show irregular curved lines.

As with most flerfs, he shows zero calculations to back up his claim, and relies on his audience thinking that big scary numbers means that stars should exhibit a huge amount of proper motion over the course of a single night. In reality, the proper motion of stars is well understood by astronomers, and we see the exact amount we should expect. Dubay using the term "contradictory motions" shows he doesn't even have a foundational understanding of net velocity.

Star trails on a flat Earth

Flatbrains think the stars are embedded in the firmament or dome, or whatever they conjure up to solve the current corner they painted themselves in. They aren't smart enough, however, to realize that if there was a dome rotating with stars going around in circles, the stars would only trace a circle when the observer is at the north geographic pole. Everywhere else, the trails would trace an ellipse.

Just look at a circle held sideways. It's an ellipse, dummies. But we don't see that. Flat Earth falsified. Again.

But it gets worse for them. Opposite rotating celestial poles is unchallenged evidence the Earth is a globe and a another complete falsification of the dirt pizza. They play word games like "do the stars go east to west around the south celestial pole"? As if this weasel attempt is going to hide the devastation that the actual opposite rotation causes for them.

Flat earth requires that the southernmost star trails are horizontal. If you're under a rotating Tupperware lid the outside edges will appear to move sideways. Do we see this? No. Flerfs are dumb.

Here are some examples of the actual observation: a south celestial pole seen due south from sundown to sunrise.

Here is another observation from Australia.

Polaris is unmoving

polaris is not perfectly aligned with the NCP. Each concentric circle represents a declination, separated by 20 arc minutes.

Contrary to somewhat popular belief, the "north star" Polaris is not perfectly aligned with the North Celestial Pole (NCP). It is currently separated by just under 40 arc minutes (according to Stellarium), but this number will continue change mostly due to precession. Because Polaris is not perfectly aligned, it exhibits star trails just like any other star.

Some flerfs are actually ignorant enough to imagine that Polaris is perfectly centred and will refuse to accept it when they are presented with a time lapse showing polaris doing a small circle like this one.