Once upon a time in the land of Equestria, there were two magical alicorn sisters who ruled with compassion and love for the land they called home. Like the unicorns, pegasi and earth ponies, they cared for Equestria with their grandiose powers. The elder sister, with her mighty horn, guided the sun as it glided through the Equestrian sky, keeping the land awash in golden warmth that yielded luscious harvest. The younger sister, with her gentle horn, coaxed the moon smoothly through its phases, shining its healing glow down on Equestria’s land, waters, and ponies. For many years, it was good for all.
Peaceful as Equestria was, there was strife and danger in many other lands, and the royal sisters were often called to defend their home from envious invading forces. Endless chaos and calamity. Darkening hatred and rage. Destructive appetites of power. Fierce as these battles were, the alicorn guardians rose to meet each challenge and save Equestria from doom and ensure the peaceful harmony would continue. Alas, this peace was not to last.
Over time, the elder sister began to grow resentful and jealous of her younger sibling. While the ponies cherished the cool night as a time of calming recovery and marvels that hid from the daylight, the ponies worked and toiled through the hot day, completely ignoring the golden beauty the elder worked so hard to make just right for everypony. Finally, she could take no more. Coveting the adoration the ponies gave her sister and her night, the elder sister’s heart gave into the thoughts of envy and she transformed into a wicked mare of burning fury, Daybreaker.
Challenging her sister, Daybreaker’s powers had grown strong with her rage, and she used her burning horn to hold the sun in place over Equestria, parching the land in its boiling heat. The younger sister’s heart grew heavy as she realized this was all her doing. She did not show her sister the love she so deserved and now her dearest friend had become her greatest foe. Tearful, the younger sister used the most ancient and powerful of Equestria’s magics, the Elements of Harmony, and sealed away the broken-hearted mare on the surface of the sun. From that day on, the younger princess took on the duties of both guiding the moon and guiding the sun. So it has been for almost one thousand years, her victory commemorated by the Grand Eclipse festival every year since.