My Little Pony: Defenders of Friendship
Misty, as a child/filly, was always rather enamored with stars/the night sky, but could do little about it as she was just an earth pony. She had no real magic to aid her nor wings to get to better vantage points, so all she could really accomplish was staring through a telescope from a hill.
Recently however(about a year before the present time) she got a chance to change that, as a renowned unicorn wizard in a nearby town was taking on an apprentice, earth ponies included. She managed to get taken on as his or her apprentice, and started her training. It went well for a while, but notably she slowly developed a knack and obvious interest for astronomy(/astrology).
At some point she met(/was approached by?) some sky spirits. She knew what these were and their abilities through her studies, so she took the opportunity to request a pact: she’d serve them in exchange for being turned into a pegasus pony, to further her study of astronomy.
When she got back to her wizard master’s tower and s/he found out what happened, s/he was pretty displeased(not necessarily angry, but disappointed for sure). Misty was removed from her apprentice position and left; this was about a month before present time.
Recent times have simply seen her up in the clouds studying astronomy on her own, since she now has a completely unobstructed view of the night sky.