Asteroid Impact Risk List

A handful of asteroids are kept on a long-term monitoring list because their orbits aren’t yet pinned down tightly enough to rule out a very distant future approach. The table above shows the most significant, ranked by the Palermo scale — a measure that compares an object’s risk to the natural background chance of a similar impact over the same period. A negative Palermo value means the risk is below that background level, and almost every object here sits well below zero with a Torino rating of 0 (no hazard).

None of these is a prediction of impact. The odds shown are cumulative across many possible dates spread over decades or centuries, so the chance on any single date is far smaller. As telescopes gather more observations, objects are steadily removed — Apophis and 2024 YR4 are two recent examples that were taken off the list entirely. See the close-approach calendar for objects passing soon.