Humans.

Truth or myth? Ancient lost civilization or just an old pony's tale?

No pony has ever seen one, and most haven't even heard of them. But Lyra knows that these wonderful creatures are more than just old legends, and she's going to find out... and possibly drive her roommate insane in the process.

A botched viewing spell has sent Twilight Sparkle to Earth and into the care of Kyle West. Having been turned into a human, the local species, Twilight Sparkle relies on her host to help her as she finds a way back to Equestria. And, in the meantime, she decides to learn about humans and the world they live in; the good, the bad, the beautiful and the ugly.

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The year is 2154, Humanity is on the cusp of interstellar travel, with the earth united under a single banner. Then an anomaly is detected, 0.75 light years from the sun a Wormhole has formed, large enough to swallow a planet and stable enough to stay open for years at a time, in a rush of scientific progress a vessel is built and crewed with the cream of humanity, the best astronauts from around the solar system.
Then it sets out across the stars, a physics defying engine driving the ship towards this gateway to places and times unknown.

A universe away, a purple coated unicorn trains her telescopes to the night sky, and notices a strange object in the sky. A hole in the endless dark between stars, through which another dimension can be seen.

"It's so nice to see you again!" said the thing that was not Celestia. "Oh yes, I know who you are, Twilight Sparkle. I had a taste of your magic the first time we met. Mortals forget things so easily, I find. Allow me to refresh your memory: you tried to kill me. But you failed, Twilight Sparkle. You only mostly killed me. And I guess that makes you one very unlucky little pony."

The Cutie Mark Crusaders ask Rainbow Dash and Fluttershy about what happened just after the events of the Cutie Mark Chronicles; specifically, what happened to Fluttershy and Rainbow Dash immediately after the race. Reluctantly, Dash and Fluttershy delve into a tale. A tale of a young Fluttershy's amazement at the world she had landed upon, and a filly Dash's desperate quest to save her from that most evil of places: THE GROUND.

A fellow pony notices that Princess Luna may have a serious problem: there is a small, sentient race inside her mane and they have been living there for quite some time. Luna must decide what to do about this.

A random short story I made to help bring the smiles.

--You will most likely enjoy this story if you also like:--
Luna freaking out
Celestia being totally chill
Sea ponies!
Explosions taking place inside people's hair
Entire wars taking place inside people's hair
Absurd and Absolutely Delicious Comedy
If you liked Mic the Microphone's Audio Version of this story:
https://www.youtube.com/watch?v=WIY268lNxeU

The history of Princess Celestia and Princess Luna is somewhat a mystery. We know little about their dark past, so why not shed some light on the topic?

Princess Luna plans to visit her sisters student in Ponyville, but ends up talking to her number one assistant instead.

Everypony knows the story about Nightmare Moon, and how she was defeated by the Elements of Harmony at the hooves of Twilight Sparkle and her five friends from Ponyville. What most ponies are unaware of, however, is how the situation unfolded from the point of view of Nightmare Moon and her counterpart, Luna of Equestria.

Luna has had enough of Celestia's games, and has found the perfect means of revenge. Using a long-forbidden spell, she transforms her sister into little more than a small filly, all so she could pull the greatest prank ever. Unfortunately, she soon learns that before you fool around with dangerous magic, you really need to read the fine print...

A sequel can be found here.