Luna and Celestia never get to spend much time together; even less so after this weird size thing happened. Luna's taken it well though, and the populace never broke out into a full panic, so that's a victory. Probably helped that the growth didn't happen all at once. While the few days the growth slowly occurred over were worrying for everyone, it gave them all time to try and process it.

Still though, Luna's been lonely lately, what with her sister being asleep all night and whatever night owls in Canterlot preferring to keep their distance lest they be smooshed accidentally. Still though, Celestia does what she can to spend some time with her sister when she's able. She knows how much Luna needs the comfort. And Luna's sky has always been so beautiful - no harm in staying up an hour or two later to stargaze with her sister, right?