Fraction of impactors discovered at least X (time) before impact, shown for four size bins (10–20 m, 20–50 m, 50–140 m, and >140 m). Values represent cumulative fractions of the full impactor population in each size bin discovered with warning times ≥X; the ≥0 bin corresponds to discovery just before the impact. The y-axis is logarithmic. Discovery probability and warning time increase strongly with impactor size, with small objects rarely discovered far in advance. Most discovered impactors receive warning times of only weeks to months, while year-scale warning is rare.