Princess Celestia is without a doubt one of the most powerful magic users in all of Equestria. And part of the reason is that she's tied to the Sun as her magic source. But what ponies don't know is that her body can adjust to accommodate the amount of magic she has stored within her.

A guilty pleasure that she has is absorbing all of her magic into herself by calling on all of the powers of the sun. Her little ponies have no idea just how much magic she holds back. Celestia grows to a gargantuan size, holding the entire planet in her magic as she goes for her nightly walks.

She smiles gently at her microscopic ponies in her grasp, along with the other of equally tiny creatures on the planet she's holding, nuzzling them against her cheek. "Ready to accompany me on another nightly walk my dear little ones?" Celestia giggles, igniting her horn and creating a road out of stardust and light, sauntering along it as she goes on another walk though the galaxy accompanied by her little ponies

Thank you to juanchongo for the picture!