Celestia for a 1000 years has been working day and night to bring either one into the sky, literally, but no amount of godlyness is going to stop the simplest of ailments from befalling her, goodly enough its not all that bad... just that she's not 'allowed' to touch another celestial body for awhile, and that means the long reigning monarch has to lie down and let somepony else get saddled with her job. As helpless the princess feels, its not all that bad being on vacation...

What happens when someone breaks their limit, what if they want to go even farther? In Rainbow's case, she went beyond anything she could even think to accomplish, but it will take time for her to understand. She has help but the actions she will take will decide more then just the safety of Equestria but the fate that bind their world to many. Rainbow will learn great things, important lessons, she is the first to enter this realm, but she will not be the last to explore.