Twilight panted as she fluttered up to the cloud, slumping into the soft surface of the thing as soon as she landed. “What,” she wheezed, “Did you need me to come… all the way… up here… for?”

Rainbow Dash snorted as she landed effortlessly on the cloud beside her, not even winded. “Seriously, Twilight? We’re only five miles up!”

Twilight’s chest heaved. “Tell that,” she gasped, “to my lungs.”

“Come on. It isn’t that bad.”

Twilight tried to glare at Rainbow Dash, but her eyes fell from her friend to her own hooves. Below, she could see Ponyville spread out beneath her, the colorful houses stretching out over the hills and across the valley like a splotch of paint. Her eyes went out of focus for a moment before she sat back on her haunches. “Too high.”

“Oh come on, we’re only halfway to the top.”

Twilight shook her head. “The top… of where?”

“The sky, of course!” Rainbow Dash waved her hoof upwards. Far above, the Sun shone down on them, the great circle seeming larger amidst so much unbroken blue sky.

Twilight took a deep breath, then let it out. “Rainbow. There is no top to the sky. It isn’t a physical object. We’ve been over this before.”

“Heh. Shows what you know.”

“Everypony knows that, Rainbow.” Twilight shivered again, ducking down close to the surface of the cloud to shield herself from the frigid breeze flowing over the cloudtop. “It just goes on forever. That’s why the air gets so thin.”

“Then why doesn’t all the air go away, huh? I’m a weather pony, Twi; everypony knows air goes from high pressure to low pressure.”

“Because of gravity.” Twilight’s lungs burned as they tried to make the most of the thin air. “The planet pulls it down against itself, like a blanket.”

“You’re wrong. The sky is up there, keeping the air in.” Rainbow Dash pointed with her hoof. “I know! I felt it!”

“You were probably hallucinating.” Twilight sucked in another lungful of precious air. “It happens when you’re suffering from oxygen deprivation.”

Rainbow Dash puffed up. “What about the Sun, huh? Because I’ve totally touched that, too. Is that just my imagination?”

Twilight laughed. “Rainbow, the Sun is way too high for anypony to reach.”

“Oh, yeah? Then how does Princess Celestia move it?”

Twilight frowned. “It’s not that hard, once you know the trick to it.”

“And how do you move it if it is soooo far away?” Rainbow Dash landed on the cloud in front of Twilight, making her friend take a step back.

“Magic. There’s a trick to it. You don’t lift it like a chair or something. It’s completely different.”

“Yeah, because it’s part of the sky! Look, I’ll fly up and prove it.” Rainbow Dash pumped her wings, launching herself off of the cloud, up towards the too-big golden disc of the Sun.

Twilight winced as she held up her hoof, trying to cover the orb. “Rainbow, stop! The air is too thin! You’ll pass out!”

“Hah! Show’s what you know. I’ve made it before. The air isn’t THAT thin.” Rainbow Dash flared her wings before pumping them back against her sides, rapidly climbing as Twilight bit her lip and watched. The form of the pegasus became increasingly small as she climbed higher and higher, first the size of a bird, then little more than a sky blue speck against the great orb.

Twilight squinted. How high was the pegasus altitude record? She couldn’t remember now. Was she suffering from oxygen deprivation already? She glanced down at her hooves, eyes watering as the cold breeze blew into them from across the cloud. No, she could focus. Her eyes flicked back up; Rainbow Dash seemed to have stopped. Was she falling? Could she go no higher?

The speck seemed to hesitate for a moment, then moved a short distance across the disc of the Sun. Suddenly, it stopped, and with a sudden jerking motion, seemed to try and push back into the impossibly distant orb.

Far above Equestria, the Sun flickered for a moment as a single perfectly black square appeared on its surface, outlining the blue pegasus who made it.