During the course of Your Name. (orig.: Kimi no na wa.) we learn that in Mitsuha's time her home town Itomori is about to be hit by a splintering comet. When Taki in Mitsuha's body is going to save the town together with her friends, they mention the fact that the region was already hit by a meteorite a thousand years ago, which actually created the lake that Itomori is built around (transcribed by me from the German translation):
Sayaka: But, it's improbable that it happens, right?
Tessie: No, not necessarily! Do you even know how the Itomori lake was formed? By a meteorite crash, thousand years ago there already landed one here.
Mitsuha (Taki): I understand, that's why!
When hearing that, Mitsuha/Taki remembers what I think to be a painting of the comet in the shinto cave where he drank Mitsuha's sake. He seems to have a realization of some kind, but it's unclear to me what he "understands". It might be just the realization of why there was a painting of the coment at the shrine, but even then, it's still quite a coincidence that the Itomori region is hit by a meteorite twice (and albeit not at the exact same place, then at least quite closely, close enough for both craters to merge into a bigger lake after the impact).
So, is there any further connection between the meteorite impact a thousand years ago and the one in 2013 that Mitsuha and Taki try to save the town from? Is it even related to the whole body switching, too (earlier Taki/Mitsuha suggests that the body switch "dreams" could be there to warn/prepare them for the meteorite hit)?