Leaning back in thought over her suggestion, the Doctor felt some of his hesitation creep up. "Ah... right, the perigee! After this, there'll be another September 9th. Three in one year, 2014 is a brilliant year. See, they don't normally occur so often, in fact--they won't again until 2034."
Normally, he would jump at the chance. The Doctor loved seeing things, old and new, didn't matter if he'd seen them before. This was a different universe. He wasn't even supposed to be alive for much longer, not with this face, so he appreciated things far more than ever before. He'd been keener on keeping to himself, however, and being offered the invitation of spending time with one another made him realize how poor he'd been about doing it at all.
"'Course we can go," he said, some guilt hanging in his voice despite the smile the Doctor promptly wore. "Wouldn't miss it. Well, suppose technically I can't miss what I've already seen, but... we'll go. Anywhere in particular you wan to see it from, Rose?"