The Ponyville schoolhouse is a scene of chaos. Fillies and colts gallop around at random, overturning benches, tripping over school bags and sending lunch boxes and pencil cases flying across the room. It is difficult to make out what anypony is saying with all the shouting and screaming. On the other side of the room is my sister, surrounded by a crowd of adoring young fans.

We are both here, at Cheerilee's invitation, and with a little prodding from Twilight Sparkle, because it is Equestrian Science Week. The class is doing a project on 'The Sun and the Moon' and they wanted someone qualified to talk about it. What professionals could be better qualified than my sister and I?

Luna is the real star. I am the figure of authority whom they are too shy to talk to. They respect me. They admire me. Some of the older children come and politely ask me what grades they need to work for the government, or occasionally, how I get my mane and tail to look like shimmering sunlight, but mostly they just ignore me. Luna is the one they love. She tops every childish ‘Best Princess’ poll. The one who comes into their dreams, scares away the monsters under the bed and helps them to deal with their fears and to sleep soundly. She is also the one who comes to play with them every Nightmare Night, dressing up as Nightmare Moon to give them a fun scare, before sharing the sweets she ‘extorts’ from them in an all-night party.

I must not begrudge my sister her popularity. She has endured far too much isolation in times past. I must be happy for her that today they are literally climbing on top of her and rubbing themselves against her legs like pet cats.

Like Twilight once did to me.

Cheerilee stomps a hoof, and by some inexplicable schoolteacher magic makes the foals all stop screaming and take their seats. A little colt, with a floppy mane and a white coat with dark patches, lingers for a moment looking at Luna. He says, “You're the best princess!” with a cute Trottingham accent, before running to his place.

Once all the foals are seated, Cheerilee addresses the class.

“Good morning everypony. Today we are very lucky to have Princess Celestia and Princess Luna here to tell us all about the sun and moon.”

She beckons me to come forward and I take my place at the front of the classroom. I smile at the class and begin my lesson.

“Hello everypony. I’m going to tell you all about the sun. The sun is the star which provides all the light and heat to make it bright and warm during daytime. Although it looks small, it is actually much bigger than all of Equestria—it is just a long way away. The surface is a glowing sea of hot gas…”

They smile politely, but they are not taking it in. When I told Twilight about solar flares, the corona and the nature of sunspots, she would look at me with eyes hungry for information, lapping up everything I said. Then the next day she would run up to me with a notebook full of algebraic equations, eager to tell me about a new theory she had read about. These foals are not like that. It’s not their fault. They cannot sense the surface of the sun like I can, and admire the beauty of the epic turbulent storms on the photosphere. Neither could Twilight of course, but Twilight was special.

I finish as quickly as I can, and let Luna take my place. Luna looks at the class with a big smile and begins with a question.

“Who can tell me what the moon is made of?”

“Cheese,” says a small giggling little filly.

“No,” says Luna. “Cheese would be a silly thing to make a moon out of. The ursas would eat it. The moon is made of grey rock. It does not emit light of its own, like the sun does, but we see it brightly lit when the sun shines onto its face. If the sun is in front of the moon, we see a full moon. If it is to one side, we get a crescent, half or gibbous moon as only part of it is illuminated—come Cheerilee! Let us explain.”

She directs a somewhat bemused Cheerilee to the centre of the floor.

“You are the Earth.” Luna puts the teacher in her place. “Celestia is the sun, and I shall play the moon. When I am between you and the sun, it is a new moon and the sun is behind me.”

She faces the class so I am looking at the far side of the moon. She then orbits around Cheerilee to illustrate the lunar phases until the teacher is looking dizzy and the class are all laughing out loud.

“But the most spectacular sight is when the moon is directly in line with the sun, in a solar eclipse.” She stops in front of me. “It blocks out the light creating a very special type of night while the sun is still above the horizon.”

Luna’s enthusiasm is infectious and the class are now following every word she says with eager expressions on their faces.

“Can you do that?” asks the little colt with the patched coat.

“Of course I can,” Luna replies smugly. “Or rather we can.”

She looks at me. She is right. The precision positioning of two astronomical bodies above the horizon is a two-princess job. I had forgotten all about eclipses. We used to do them for fun in the days before her exile, but I could never have simultaneously positioned the sun and moon on my own. A total solar eclipse has not been seen in Equestria for over a thousand years.

“Can you show us now?”

“Well…” Luna turns to look at me with a cautious face.

“Please Princess Luna! Please! Show us an eclipse!”

Luna continues to look at me and I can only nod to give her my agreement. When little foals ask for something so nicely, it is only right to move heaven and earth to make it happen. Luna beams with satisfaction.

“Outside!”

The foals happily trot, skip and jump outside. In the school playground they immediately stare up in the sky looking towards the sun but Luna is airborne before we know it, spreading her wings wide to block the light.

“DO NOT LOOK DIRECTLY AT THE SUN!” she bellows.

“But—” replies a young foal.

“If you look directly into the sun for more than an instant, it can permanently hurt your eyesight,” she says sternly. “If you accidently get it in your eye, you will blink and it is okay. But you must never deliberately look at the sun—”

Her stern voice has shocked the class into silence, but the mood lightens once she starts smiling again.

“—unless you are wearing proper eyewear.”

She takes out a bag of eclipse-viewing goggles and passes it around the class. Did she have that ready all this time? It seems she has prepared for this stunt. Once all the little ponies have dark lenses in front of their eyes, she lights up her horn and the moon slowly rises above the horizon, heading towards the sun.

Watching the moon move across the daytime sky I wonder if this was such a good idea. We are going to have to face the music when we get back to Canterlot. The castle Public Relations Office do not like it when we have the sun and moon in the sky at the same time. This will make them hit the roof—the first eclipse in Equestria in over a thousand years and we ‘forgot’ to warn them in advance. I picture the despairing look my PA is going to give me. The retired officers and civil servants in suburban Trottingham and Hoofington will have a field day writing letters to the papers. It will probably cause a stock market crash in Manehattan, and we will have to send a cake-laden peace envoy to Griffonstan and Muledavia in case they take it as an act of aggression.

“Keep the sun steady Celie.”

Oh well, it’s too late to back out now. As the disk of the moon touches the sun Luna joyfully shouts out, “First contact!” Then she begins a countdown.

“Ten… Nine… Eight… Seven…”

She has now stopped using magic as the sun and moon are in the right position and we just have to wait as the earth rotates around to bring the sun, the moon, and us into alignment. It grows dark towards the west as the moon’s shadow rushes towards us.

“Six… Five… Four… Three… Two… One… Zero! We have totality!”

The sky turns to twilight and it feels cold. As the silhouette of the moon moves into place around the sun we have a momentary image of the diamond ring created by the sunlight flitting through the valleys between the mountains on the rim of the moon, then a circle of complete blackness.

“You may now remove your goggles.”

It is now dark. The stars are visible in the sky, and we have the vision of the solar corona around the black disk obscuring my sun. The shimmering white light surrounding the black hole in the sky. It is beautiful. I had forgotten just how awe-inspiring the sight is.

“Now,” says Luna with a proud voice. “You can admire the hidden glory of my sister’s sun.”

On hearing those words I realise that she is looking, and pointing a hoof at me. The foals are also staring up into my face.

“The beautiful corona – the wispy stream of hot gas which extends far from the sun, but which we can only see when the dazzling light of the solar surface is behind the moon. Celestia you may hide your best artwork, but I know how to reveal it.”

“That’s so cool,” says the little colt. “How do you do it?”

“It’s just a plasma of super-hot ions and electrons,” I mumble, “streaming outwards, and shaped by the magnetic field of the sun.”

“It’s beautiful, like your tail,” says a young filly.

“Not quite…”

The foals are now all crowding around me. Staring alternately at the eclipsed sun, and up at me. I smile, enjoying the unexpected attention. Luna now has a smug grin. She has planned this all in advance, remembering, where I had forgotten, that while the moon is at the front of the stage, the sun is the real star in an eclipse. The moon can only be admired in the light of the sun. Likewise you can only look at the sun, when the light of its surface is blocked by the moon. I gently reach over the mass of little ponies to nuzzle my sister’s neck. She really is best princess.

Author's Notes:

In our world eclipses are rather more difficult to engineer, but rather easier to predict.

Europeans: Don't miss tomorrow's eclipse. March 20, 2015 09:47 UT +/- an hour or so depending on your location. Only the Faroe Islands and Svalbard will see totality. There will be a webcast. Remember: Do not look directly at the sun. If you don't have eclipse viewing glasses, then build a pinhole camera (it's dead easy).

Americans can look forward to August 21, 2017, when a total eclipse will sweep across the country from Oregon to South Carolina.

Everyone else, check out the NASA eclipse web site.

Cover art vectors by Flower Jewel, Sulyo, Ashidaru.