Twilight is so cute in this comic…  
Wait, heliocentric orrery?  
BLASPHEMY!

@JP
 
I think they look like weights which turn it over when the top bulb empties.
 
@UbberNoober
 
Even a specialized school will need some support courses: math, history, lit, biology, natural physics, et cetera. Also, remember that we have a zebra who does alchemy, so if she teaches any magical courses it might be something along those lines.

I wonder what the significance of those blue orbs around the hourglass is? Because they just counted down by one. And is that Jupiter in the orrery?

Yes, let’s yell at the little filly who loves learning so much she’s overcome by her enthusiasm in a library. Great plan, guys.

What’s a muggle doing teaching unicorn foals?

 
DEATH BECOMES MUFFINSHIRE