"We just hit two point five millibars!" Spike’s voice rattled up through the brass speaking tube.
Twilight tentatively pressed the middle lever.
The Telescope moved flawlessly on its new bearings. Feeling as though it had never been broken in the first place.
True to her words, Applejack, a humble farmer, had improved on the design considerably. The Telescope now focused in and out, whisper-quiet. Safeguards had been installed which made sure the mare’s help would never be needed again, but a small part of Twilight felt saddened by that... and even more so when she’d left. Needed, no, but wanted?
Still, even with this new revelation, she was glad Spike hadn't told Applejack about the mare on the moon. He hadn't seen the hoofprints like she had; he still probably thought it was a fault with the Telescope. Twilight had believed that, too, hadn't she?
For now, the Mare on the Moon remained her little secret.
She widened the field of view, scanning the lunar surface for that pinprick of blue on white desert. There, a few... kilometers? Yes, about that far from the edge of the darkness as the moon started to wane.
Why not stay at the far edge, then, where it was always light?
She narrowed the field of view until she could see the mare fully. She was galloping now, looking back over her shoulder, mane and tail streaming behind her – caught in that breeze that couldn’t be. The Telescope had to move fractions of a millimeter to keep her tight in the unicorn's view. What was she running from? The darkness, obviously, but...
Twilight leaned back away from the eyepiece. This mare was like a foal on the beach, playing with the lapping tide; running with it as it receded, and then away as it pushed its way back to shore, each cycle running the course of a month.
She wasn't just lonely. She was bored.
"Hey, Twilight, can I see?"
Spike's disembodied voice rattled her out of her revelatory reverie. "See what, Spike?"
"The Mare on the Moon. I want to see her!"
Twilight considered it a moment. Was there really a reason to keep it to herself? Why hadn't she reported it to the Princess yet? The thought of telling the Princess of Mourning about this felt... wrong, for some reason. Very wrong.
"Sure, Spike. Make sure the boilers won't explode without you, and come up here. Take the ladders, though, we don't want to waste pressure on the elevator."
"Gotcha. Be there in a few minutes."
Twilight would feel more guilty about sending Spike up the ladders if she didn't already know two things: that the elevator was up here at the top, and she would have to spend pressure on sending it down as well as back up, which was the cold logical reason. The other was that Spike liked climbing. Maybe not that much, no, but it was the closest he could come to flying, since his wings hadn't grown in yet. Those claws of his made him a better climber than any pony, and he took no small amount of pride in that.
Twilight tracked the galloping mare on the moon slowly, the minutes passing in breathless seconds. She jumped when Spike tapped her on the shoulder.
"Oh! I kept her in view for you. The telescope should be moving at the right speed to keep up with her, now, so all you have to worry about is looking down the eyepiece."
Spike grinned as Twilight vacated her little brass-and-velvet seat affixed to the Telescope's side and Spike plopped down in her place, stretching his neck to reach the eyepiece.
"Woah, she's really moving, isn't she?"
"She's trying to outrun the darkness. I think it's like a game to her."
"Boring game," Spike grunted. "Not like there's anything else to do up there, though, is there?"
"No, I suppose not."
"How long do you think she's been up there?" Spike wondered, eye never leaving the harsh metal eyepiece, pressed to it like not even Twilight dared to with her far more sensitive pony physiology. Draconic skin, draconic skull, draconic eyes all made pressing into it less painful.
"I have no idea. The tracks seem to run all over the moon though. If she makes a circuit once a month... She'd have to have been up there for hundreds of years."
"The Telescope isn't broken is it? There really is a mare up there, huh?"
Twilight was uncharacteristically silent at that.
"Woah!" Spike yelped, suddenly. "Stop! Stop the telescope! Go back!"
"What? What happened?"
"She stopped running, and the Telescope just shot right past her!" Spike jumped out of the chair, giving Twilight a worrisome look. She took his place, magic gripping the lever again and pulling it gently back.
The Telescope moved less than half a millimeter on its bearings, but its view shot back across perhaps a hundred meters, maybe two. The Mare on the Moon was standing, stock still, looking up into the sky...
Directly at her.
Twilight rocked back in her seat, tearing herself away from the eyepiece. Spike tugged at her fur, like an anxious child years his younger would.
"What? What happened? Why'd she stop?"
"I think... I think she knows we're watching her."
"How?! Is she mad?" Spike stared up at the moon, a child awaiting judgement from a parent, hand caught in the cookie jar. Twilight knew how he felt.
Looking back into the eyepiece, she saw that the mare was still staring up at her – at her – across the great span of the aether between them. She shook her head slowly, mane still caught in that wind that couldn't be, and started running again. The spell was broken.
"She knows," Twilight whispered.
"Did you see her face, though?" Spike whispered, as if the Mare could hear them, even now.
"I did. Why?"
The little dragon looked at her a long moment, then down at himself, claw scratching idly at a soot stain earned from working the boilers. Finally, he worked up the courage to say what he thought. "She looked just like you did, when Applejack left yesterday."
Twilight's heart froze, an unbeating block of ice weighing against her chest, as she looked up at the bright moon above.
A decision was made.
"We've got to find some way to talk to her, Spike."
"What? But... but nopony has ever sent a message across the aether before! Magic won't go through it, even if you got the Princess to help you!"
It was true. The Princess of Mourning was strong enough to spin the world, but even she had stated that it was impossible to send magic out beyond Equestria. A single tear had fallen from behind the black veil that she was never without, not even alone, so Twilight knew the truth of it.
"Then we can't use magic," Twilight agreed, pushing herself away from the telescope and peering down, down into the bookshelf labyrinth below, and she made a decision. "Tomorrow, I'm going to the university. Science will succeed where magic has failed."
"You sound so sure. You haven’t even made me double-check anything! How do you know?"
Twilight stepped into the elevator, Spike plodding along behind her, everything about his expression and body language pleading for an answer.
"Because it has to, Spike. I know, because it has to."
Whatever Spike's thought on that matter, he remained silent the length of the elevator ride down.