Distance of closest approach

When things move around each other in space, sometimes they come really close, like when you give someone a high five. The distance of closest approach is just how close they get to each other. It's like when you play tag and you try to get as close as you can to the other person without actually touching them. Scientists use the term "distance of closest approach" to talk about how close two objects come to each other when they move around each other. It's important to know this distance because it can help scientists understand how objects in space behave and interact with each other.