How astronomers quantify and communicate asteroid collision risks using the Torino Scale and the Palermo Technical Scale.
1. The Torino Scale (0 to 10)
Created for public risk communication, categorizing hazards by collision probability and kinetic energy:
- **0 (White)**: No Hazard.
- **1 (Green)**: Normal discovery passing safely.
- **2–4 (Yellow)**: Merits attention by astronomers.
- **5–7 (Orange)**: Threatening close approaches.
- **8–10 (Red)**: Certain collisions ranging from local destruction to global extinction.
2. The Palermo Technical Impact Hazard Scale
A continuous logarithmic scale comparing predicted impact probability against background annual collision rates:
$$PS = \log_{10} \left( \frac{P_i}{f_B \times \Delta t} \right)$$
Values above 0 indicate risks exceeding the background threshold, requiring prioritized radar and telescopic tracking.