“Near-Earth asteroid” is an address category for objects whose orbits enter Earth’s broad neighborhood around the Sun. YR4 is a vivid example because its stretched four-year route sets up a close passage through the Earth–Moon system in 2032.
Think of two runners using paths in the same enormous park. Their routes may cross the same area, but they still need to arrive at the exact same spot at the exact same time to collide. Astronomers track both the route and the timing.
YR4 earned extra attention because early measurements placed Earth inside the range of possible 2032 positions, producing impact estimates that briefly climbed above 2%. More observations refined that forecast. What remains is an exceptional near-Earth encounter: about 173,000 miles from Earth’s center and far closer to the Moon.