Talk:Princess Luna/@comment-24908786-20140603165042/@comment-24908786-20140802133638

Actually, according to the Journal of the Two Sisters, Celestia and Luna's manes and tails probably started sparkling and flowing as soon as they got their cutie marks after being asked by Star Swirl to lower the moon and raise the sun in the belief that doing so would revitalize Celestia and Luna since Alicorn magic was stronger than Unicorn magic.

When they did it, the power of getting their cutie marks and performing their destined duties for the first time enabled their manes and tails to start sparkling and flowing from then on. The only times that their manes and tails stopped doing so, was when they either were severely weakened, unconscious, or lost their magic, as was what happened to Celestia with Chrysalis and Nightmare Moon, and to both Celestia and Luna in Twilight's Kingdom.