Impact-Risk Scales

A more technical, logarithmic scale used by specialists to rank impact hazards against the background risk of a random impact of the same size over the same time. Values below zero mean a threat less than the everyday background; above zero warrants attention.

A 0–10 scale, like a hazard traffic light, for communicating the risk of a near-Earth object to the public — combining impact probability and energy into a single colour-coded number. Apophis briefly reached level 4, the highest ever, before further observations returned it to zero.