Unbeknownst to all but a select few, Equestria was doomed.
Not today, not tomorrow, not even in a year, but within the next few decades, their world would meet its end. A fiery end.
It was perhaps two years ago a group of astronomers suspected the sun was nearing Equus each day. At first that had quickly dismissed the notion as absurd, but a few dedicated themselves to tracking and studying the movement of the sun. Not across the sky, of course, as Celestia controlled that. But towards the planet itself? A few months of intense observation, a few minor eye injuries, and thousands of pages of calculations and they determined the sun indeed was set on a collision course with their planet. Even worse, it was accelerating.
With all their evidence gathered, they presented their case to Celestia, who, to their grateful surprise, took the matter quite seriously. Over the next few weeks a team was assembled, with aid from the crown itself, and her gifted and studious pupil Twilight Sparkle was given charge of the project. Their mission was to determine if and when the sun would collide with their planet—as well as any countermeasures that could save their world.
After much discussion Princess Celestia decided to hold off on a public announcement. Such a thing would simply cause mass panic and hysteria among their populace. She knew her duty to the other leaders of their world, however, and requested personal audiences with them, and made it perfectly clear she wished for the knowledge to remain out of the public eye. Some agreed and offered their support, while others merely scoffed at the notion. Most were confused as to why it was a threat in the first place, after all, didn't the solar princess control the sun?
This was a question Twilight herself had asked her mentor early on in the project. As it turned out, the methods behind Equestria's celestial cycle were quite complex and unique. It was believed long ago the small sun naturally orbited the planet. At one point the unicorn tribe took it upon themselves to aid the orbit of the sun and at some point later, either due to an unknown cosmic event or simply as a result of their meddling, the sun required more and more interference to continue a normal path. During their rise to power, Celestia and Luna took up the duties of managing the sun and moon respectively.
Contrary to the belief of most ponies, Celestia did not simply reach out with her magic and "grab" the sun like any common object. While she was powerful, the sun was much too large for that to even be feasible, and the magical field of Equestria didn't reach far enough past the planet to make it possible. No, instead she used her immense power to concentrate magic at the edge of the field, creating a massive point with considerable gravity, allowing her to gently guide the sun along. While she needed to apply more effort during dawn and dusk, when the sun needed more force to travel around the entirety of the planet during their night, the presence of her ambient magic on Equus was enough to keep it guided during the day. Twilight found this fascinating. After all, while she was a studious unicorn, never before had she even thought there was such a difference between what ponies thought Celestia, and her sister, did to control the celestial bodies, and how the actually did so. It wasn't a powerful television spell, rather, Celestia's mass was so great—er, her magical mass, that is—that it created a gravitational well targeted at the sun to help it orbit the planet.
It was disheartening to Twilight that the issue of the sun approaching their planet at an accelerating rate couldn't be fixed so easily. No Elements of Harmony, friendship, or Celestia's raw power could save them. It was a simply a scientific issue—something which the unicorn would have found very exciting, if it wasn't the lives of every being on their planet at stake.
And so with the resources and researchers provided to her, she got to work. At the current rate, it would take forty years for the sun to impact Equus, they first determined. This number didn't mean much, though, as once they extrapolated the rate of acceleration, their planet could meet its end in as soon as twenty years, perhaps even sooner. They didn't know why the sun was on this course. Perhaps it had always been doing so, just too slowly to be noticed, or more likely perhaps a large asteroid or similar object either impacted the sun or adjusted its orbit enough to send it towards Equus. No matter the cause, they set to work finding a solution.
Many solutions were proposed, but none were good enough. The problem at hand was simply too difficult to be solved through any means they could think of. Celestia's magic, and Luna's if she attuned her magical signature to the sun instead of the moon, was not capable of sending the sun further away. The leverage their magic had was too limited by the magical field of Equus to exert the necessary force.
The sun's size made it impossible to move backwards, and similarly it was unfeasible for their planet to somehow be moved away from the sun. There was nothing large enough to impact the sun to propel it away from Equus, except for perhaps the moon, which would do its job too well and leave their planet dark and icy. The moon was similarly doomed anyways, as within a few short years the interference it would face from the closing sun would cause it to lose orbit and fly into the depths of space.
Months turned into years, and Twilight felt the onset of hopelessness. Celestia's kind words and the support of her friends kept her spirits up, but it was difficult to maintain faith in herself after countless hours of work and nothing to show for it. The other researchers she worked with were depressed. She tried to keep their spirits up but it felt useless after some time. They were likely going to all die, and they knew it. The despair began to leak into the public sphere, where rumors swirled about that the Princesses were hiding something disastrous. Nopony knew for sure, but they speculated. All of the top scholars and scientists in Canterlot working around the clock, for months on end? A great and terrible foe was lurking in the shadows, perhaps, or maybe a deathly plague with no symptoms was spreading.
One late night, Twilight found the terrible truth. It was so obvious, and she mentally slapped herself for missing it earlier. Celestia was so attuned to the sun, that her ambient magic provided enough focus in the magical sphere surrounding the planet to create a gravitational pocket which directly influenced the sun, allowing it to maintain a constant orbit around their planet every day. But it was not perfect. The magic-induced gravity was too focused, it could not be spread out like a normal planet's mass would, and as a result the sun had a slightly elliptical orbit. The solution, thus, was to adjust the amount of magical gravity produced to keep the constant orbit.
Unfortunately, this meant that over the centuries they had been controlling the sun, it had been inching closer and closer as they fixed the elliptical nature of the orbit, until at some point it came close enough to gain momentum and begin traveling towards their planet at a steady pace. As it drew closer to the magical gravity as well as the planet's gravity itself, it began to slowly accelerate until it was moving fast enough to be noticed, which triggered their realization that their world was ending in the first place.
So how could it be fixed?
Many days of work, calculations, and charting followed, and Twilight realized there was a potential solution, one that would save Equus. If the sun had its orbit accelerated to a high degree, it would enter a long, elliptical orbit, and which over time would return to normalcy while also bringing the sun a safe distance away from the planet, where it would no longer be headed on a collision course with the planet. In order to make this work, however, the magical gravity which influenced the sun's orbit in the first place would need to be removed. Sure they would have to deal with odd day and night cycles well into the future, but at least life would persist.
Twilight was excited, happier than she had been in months, no, years in fact! She didn't let on to her discoveries, not yet anyways, as she wanted to be completely sure the crisis could be averted before spreading the good news. But she knew the math and science were there, the calculations were checked over and over again, and finally after a trying ordeal, she could see the light at the end of the tunnel.
Until that one afternoon.
"Not quite, Twilight. It's closer to the cloud-walking abilities of pegasi in that regard, not active magic, simply the result of the innate alicorn magic in my presence," she had said.
Twilight's teacup shattered across the stone patio.
She offered a hasty apology and excuse and hurried out, straight to her lab.
It couldn't be. It couldn't be! Twilight checked everything again, from the beginning, but much to her dismay, the theory held true. But there had to be a way for the princess to disable the ambient magical gravity she produced for the sun, right?
She spent weeks looking for another way. Gently prodding Celestia for answers, researching what few books were dedicated to the magic of alicorns, and then to ponies themselves. She completely dedicated herself to the search, but nothing could be found. The innate magic couldn't simply be disabled, after all, it was utterly tied to a pony's life force.
Life force.
Dark bags grew under her eyes. Some days she walked into corners and chairs, unable to see straight from her lack of sleep. Those around her urged her to take a break, to rest, but she would not, she could not. There had to be another way, she kept telling herself, yet after all the studies, there was not, and she had to accept it.
She spent many nights awake, crying softly into her pillow.
Faced with such terrible, terrible truths, she wished she was somepony else.
Not the one in charge of this project.
Certainly not Celestia's student.
Days passed, and Twilight came to the terrible realization. The beloved Princess Celestia, her mentor which she adored, was indirectly responsible. Her ambient magic was too powerful, the force it exerted on the sun too great, and after centuries the negative effect it had was apparent.
She loved her mentor, who she had known since she was a filly. She also knew the lives of every pony, griffon, minotaur, changeling, buffalo, and every other creature on Equus were at stake.
Her life or theirs?
Twilight's mind raced and her heart frantically beat against her chest as she walked through the castle, her hooves padding softly against the rugs lining the hallways.
Raising a hoof, she knocked softly on the grand oaken doors in front of her.
She felt a cold sweat come over her. She felt blood pounding in her ears.
The door opened.
A warm, welcoming smile greeted her. "Twilight," she heard that caring voice say, "I'm so glad you came to visit me. I know the gravity of the situation, but it's not healthy for you to spend all your time in that lab you know," the voice admonished. "You mentioned in your letter you made a breakthrough, I'm quite curious as to what that is."
Gravity of the situation. If only she knew.
Should she lie, and simply say there was nothing that could be done?
Should she tell her mentor the terrible, terrible truth?
Arguments for and against each point flooded her mind in a maelstrom of thought.
Then, interrupted.
"Oh you look exhausted. Come in my faithful student, have some tea to calm your nerves."
She nodded wordlessly and followed her mentor into the room.
The grand oaken door closed behind her with a soft click.
