One is falling down from space, the other climbing up. Imagine if I threw a brick off a building. You are on the street and see that the brick is going to hit

One is falling down from space, the other climbing up. Imagine if I threw a brick off a building. You are on the street and see that the brick is going to hit one of two babies. You might be able to jump in front of the brick in time to collide/intercept the brick, but there is no world where you would be moving upwards anywhere as fast as an object falling from great height. Now imagine the brick can move to avoid you and instead hit the other baby. The brick changes course after you jump. That's what is happening with a hypersonic diving onto a target.