The Sparkle Letters

Princess Celestia,

It's a good thing you sent me over first, because I don't think anypony else could have survived being dropped over the ocean! I had to do a lot of flying to make it back over solid land, and it was enough to wear ME out. You have no IDEA how hard that is.

Then again, I might have gotten into a race. With some giant metal birds. Those 'humans' Twilight talked about were riding them, and when I tried to show them how fast I could go, they actually kept up! I'm kinda impressed. Those things were pretty huge, it must've taken a lot of training to get them to go so fast.

What's weird is that my Sonic Rainboom took longer than normal. I don't FEEL weaker. Twilight said that the speed of sound might be different here. I always thought I couldn't hear anything after the boom because of...you know, the boom. But I guess it's because not even SOUNDS can keep up with me! She also said something about how weird it is that I got dumped out in a different place than her, and her human friend started saying egghead things about the planet moving around on its own. I didn't really care about most of it. I wanted to know more about those huge metal birds.

Your awesome student,
Rainbow Dash!

Dear Princess,

It's a good thing you sent Rainbow over first, because I completely miscalculated the teleport spell.
As you know, all teleport spells require a reference point from which the final position is measured; for inanimate objects like this letter, the recipient is acceptable, and for short-range 'blinks' the caster is a usable reference point, but as distance increases, using small and mobile references becomes much more inaccurate. It has been noted that as one attempts longer-range teleports with oneself as the reference, one's altitude increases--this is how Star Swirl proved that Equestria is not flat. As such, long-range teleportation often uses the celestial bodies as references, because the position of the sun is always the same for a given time of day.

In this universe, the sun and moon move without magical intervention. Humans have no control over it. Their positions change slightly over time, and their orbits aren't even in sync--Barack spoke of 'eclipses', where the moon would block out the sun, not by a Nightmare's intervention, but of its own accord. I have begun work on an improved calculation, which will account for the movements of the sun and moon within this universe.