We know close stars back 4 million years, and 5 million years in future. The closest known was 0.17 at 1.2 million years ago. That is close enough to disturb Oo

We know close stars back 4 million years, and 5 million years in future. The closest known was 0.17 at 1.2 million years ago. That is close enough to disturb Oort Cloud but not be more than bright star. I’m amazed that can go back that far with Gaia satellite data. There is a limit where the stars involved are too far away.