the sky works by itself

Let us get one thing straight from the very beginning:

Sky Seer was not a terrorist, fearmonger, or extremist. No, no, Sky was a stallion of science. He only believed things after he had thoroughly researched and tested them.

Sure, many ponies called him stubborn, and a few outright labeled him paranoid, but as his great-uncle Maddeye always said, “There are the paranoid, and then there are the stupid.”

He purposefully ignored all the signs that his great-uncle had schizophrenia and simply stuck with what made sense: his research and science. He tested everything, from gravity to the incompatibility of magic and electricity. He even tested whether he was a pony or just a gear-powered automaton filled with blood (that was an awkward trip to the hospital), and he experimented with whether he could fly using his horn. He could, but not very well.

He was a stallion of science. All he had ever done was test things. However, one day, he perhaps tested a little too far.

He was at work, tracking the movements of the sun compared to the moon. Naturally, it all had to be logged so that the princesses could adjust it to match the animal migration patterns. It was a very important job, and he was always paid a hefty salary. Yet, something was wrong.

Every time he sent a report to the princesses telling them where the sun and moon should be, and for how long, it always happened—without fail. Every time, they were in the perfect spot. Never a single mistake. Now, that was simply unnatural. Every pony makes mistakes, he thought, so why don’t the princesses? And so he devised a test:

He would make a report suggesting that they move the sun and moon to completely wild locations, but harmless to the environment. A victimless crime, right? Not even a crime, as this would be beneficial for the farmers regarding the sun's location.

So he just… tweaked it a little. He wrote to have the sun orbit Equus in the opposite direction, along with the moon. Just a little test to see if they would do it. He was in the highest command of his job; no one would even dream of questioning him. So he sent the letter and promptly stayed up all night waiting for results.

The next day… nothing happened. The sun followed its normal pattern, as did the moon the night after. How queer, thought Sky Seer, that they didn't do what he wrote. Perhaps it was the exact one time they finally made a mistake? Perhaps they just followed the previous day’s instructions by accident?

So he sent in the same orders. The next day, no results. He did this again and again, and every single time, nothing happened. The sun and moon did what they always did: move east to west. It was… well, to Sky Seer, uncanny. They MUST be reading his notes, right? Why else would his job even EXIST?

So he decided to ask: what other explanation could there be besides the princesses making the sun and moon orbit Equus?

And so he did what he always did when he didn’t know what to do: he ran some tests.

All of them, even the ones meant to prove otherwise, pointed toward one conclusion: Equus orbited the sun, and the moon orbited Equus by itself.