The Equus calendar measures the movements of each Star Cluster as they orbit the center of the Galaxy. Remarkably at the same speed... well it would be remarkable if the Galaxy wasn't artificially created but that was besides the point!

At the center of each Star Cluster is a massive ring with an artificial environment, which generates it's own cycle of artificial light.

Luna, through the invention of the most powerful telescope ever created, discovered this. After her banishment, Celestia implemented her discoveries as the official pony calendar. Even going so far as to move the Sun and the moon around Equus according to these measurements. It was later discovered this was the same calendar all space fairing civilizations use.

A day on the Rings lasted 30 hours, with 20 hours of daylight and 10 hours of night.

It takes the Star Clusters exactly 1095 days for the rings to orbit the center of the Galaxy. Everything in the universe is synchronized to that timetable. It's how long it took everything and everyone, with magic, to age a single year.

There are 12 months in a year, with each months lasting either 80 or 90 days on the dot. Each month measures a single season on the Rings.

For Example: October was the last Summer of the year, November was the last Fall, and December was the final Winter.

However this means there are 3.6 Earth years compressed in this single years. As a result the Celestia has to have 3 sets of seasons on Equus, to keep up with the demands of nature.

The fact the Lunar cycles on the rings are far faster then any planet should have doesn't exactly help this.

There are 8 to 9 Lunar cycles a month on the rings, making for a total of 100 Lunar Cycles in a year. These cycles are frequently called "Moons" or "Weeks" and used as time measurements themselves.

That effectively means there are 10 days in a week. These days of the week are known as:

New Moon, Waxing crescent, First quarter, Waxing gibbous, Full moon, Blood moon, Harvest moon, Waning gibbous, Last quarter, and Waning crescent

However, knowing all this, with his vast understanding of the delicate tick of the cosmos to such a degree... could not help him from the horrific nightmares that could be unleashed by none other then!-

His fussy toddler...

“Aww...Dad, do I really have to go?”

“Come on Sweetie, your mom will have my head if I-”

“What if I dooooo- THIS!”

“Nice try sweetie, but after you're mommy's vicious training I have developed immunity to puppy faces. You convinced me to give you cookies before dinner one to many times for her liking."

Dinky Hooves let out an annoyed huff as she crossed her forelegs. Normally, The Doctor would respond by chuckling a bit while ruffling his daughter’s mane but this was a different situation.

“Listen, pumpkin.” The Doctor whispered softly as he gave Dinky a gentle hug. “Pre school isn’t that bad. Your mom dealt with it even with her eye condition and she managed to survive! You’ll be fine, trust me.”

“But the thing is…” Dinky muttered as she gently broke the hug and stared at her father’s eyes. “What if the kids make fun of me?... For being, no offense, like you.”

“Hmm?” The Doctor asked with a raised eyebrow. “Like me?”

“For my freaky time powers!” Dinky angrily blurted out before eeping and covering her mouth. “Um, yeah.”

“Ah, I see.” The Doctor responded as realization began to form in his mind like the frown forming on his face. “I suppose you do have a point.”

Upon seeing Dinky grow more worried, The Doctor let out a weak smile as he hugged her once more. “There, there, pumpkin. Your mother and I raised you to be tough so these kids shouldn’t be a problem. Come on, where’s that smile of yours?”

Dinky continued to sulk until a pair of hooves began to tickle her side, causing her to crumble into hysterical laughter. “Dad! Stop!” She panted between laughs.

Eventually, The Doctor ceased his tickling and was soon met with another hug from Dinky. “Thanks Dad.” Dinky sweetly said as she beamed up to her father.

“Anytime, sweetie pie.” The Doctor responded as he patted her head. “Now go help out your mother. Daddy’s got to do some tinkering.”

Dinky nodded and trotted away with a smile on her face, leaving the "lab" (AKA the "Basement"). The Doctor smiled at her as she walked away. When Dinky was out of sight, however, The Doctor’s smile crumbled into a concerned frown as he turned around and walked in front of a large police phone box. The TARDIS, seemingly there the entire time. He lightly touched it with his hoof.

“Can’t blame the dear.” The Doctor hummed to himself. “She’s definitely different than the others. They all have normal fathers, after all.”

Looking around, tempted to open the doors, but shook his head. “Darn that Ditzy. Why’d she made me promise to stop using you, Sexy? She knows how important sailing the Time Vortex is to us. I’m sure Dinky wouldn’t think of this as a bad influence”

He looked back at the TARDIS, at his sexy time machine, and he slowly grew more serious. He normally blocked out the future, after all it was much more fun to experience the universe like a 3 dimensional being... but he had been cut off for so long. Who knows how much suffering has occurred since then... or how much better the universe was without him.

He closed his eyes and removed his mental block... Equestria was entering the space age. They already had light speed ships and forged alliances with the other races of this system... so much life... but he wanted to know what would happen to it.

Unfortunately, the future that he focused on was not what he had expected. Granted he had long since learned that not everything was sunshine and rainbows, with a dash of flower petals in the case of the ponies. He understood that there would be some suffering along the way. But this… this made The Doctor’s stomach churn. He saw what he could only describe as an extinction level event. To properly go in detail over what he had just witnessed would simply be an impossible feat. And yet he was fortunate enough to know who or what was responsible for this future.

The Doctor’s teeth clenched in frustration as he slowly whispered the words that burned his hearts with utter fury.

“Reapers…” He shook his head and looked at his TARDIS, speaking to the vessel and knowing she could hear him, "The two of us have been fighting them for so long... every one of my faces does a little more to turn the war in our favor... and it is never enough. Still they claim so many worlds... so many lives lost to them... and now we can't even do anything to stop them. Those stupid Q and the other would-be-gods refuse to let an 'ascended being' interfere with wars between civilizations at equal stages of development. Of course they consider a caveman fighting against a gun as fair! There has to be a way around that... there has to be,"

He tried to think of a plan but he hadn't closed off his mind from time. He could still see into all the possible futures of the universe... and the history of futures-yet-to-be showed him what he wanted.

Much to his surprise, he witnessed a different future to this pony apocalypse. This one… this future was entirely different. The bitter death he had witnessed was no longer there and the mass extinction was no more. This one seemed more easy to describe in detail, yet this vision just puzzled him to no end. Equus still stood, countless worlds that were once lost now thrived in this possible outcome. But how? Why? What? Where? When? His head would have popped if it was not for the next glimpse of this benevolent future.

He saw himself. Looking almighty but still dumb as ever (in his own opinion anyway) in front of these… who were they? They looked more heroic and brave than himself. Were they...champions? He gathered an army. No not gathered... trained.... raised... He saw children that would grow into soldiers... and use their gifts to save them all. Could he really do that? The ethics of training an army from childhood was questionable enough... he supposed, if he gave them a choice to help after they were trained, it would be no different than a military school...

School? Now there was an idea. Unfortunately, his vision ceased, as apparently he was trying to look into his own future. There were some things even Time Lords couldn't do, even ones with a Time Agent Class... even ones that long since left their mortal limitations.

The Doctor found himself panting a bit, as just getting a glimpse of his soldiers pushed his limits a bit too far. He didn't see their faces, or even their species, but still he saw more than he should have.

The Doctor shook his head as he glanced back to his TARDIS. He could feel her reestablishing his mental blocks, to protect him from his visions, "Thanks love," He let out a sigh as he trotted back to his wife and daughter. “Well then, looks like I’m gonna have to save Equestria. But first, dinner. I hope Ditzy remembered to buy the fish fingers and custard again... maybe we will have Jelly Babies for dessert?" He hoped. This face of his was quite nostalgic after all.