| Example or Size Equivalent | Most Recent | Planetary Effects | Effects on Life |
|---|
| Supercolossal: radius (R) > 2000 km | Moon-forming event | 4.51 × 109 years ago | Melts planet | Drives off volatiles; wipes out life on Earth |
| Colossal: R > 700 km | Pluto | More than 4.3 × 109 years ago | Melts crust | Wipes out life on Earth |
| Huge: R > 200 km | 4 Vesta (large asteroid) | About 4.0 × 109 years ago | Vaporizes oceans | Life may survive below surface |
| Extra large: R > 70 km | Chiron (largest active comet) | 3.8 × 109 years ago | Vaporizes upper 100 m of oceans | May wipe out photosynthesis |
| Large: R > 30 km | Comet Hale-Bopp | About 2 × 109 years ago | Heats atmosphere and surface to about 1000 K | Burns continents |
| Medium: R > 10 km | Cretaceous- Tertiary impactor; 433 Eros (largest near-Earth asteroid) | 65 × 106 years ago | Causes fires, dust, darkness; chemical changes in ocean and atmosphere; large temperature swings | Cretaceous- Tertiary impact caused extinction of 75 percent of species and all dinosaurs |
| Small: R > 1 km | About size of near-Earth asteroids | About 300,000 years ago | Causes global dusty atmosphere for months | Interrupts photosynthesis; individuals die but few species extinct; threatens civilization |
| Very small: R > 100 m | Tunguska event (Siberia) | 1908 | Knocked over trees of kilometers away; caused minor hemispheric effects; dusty atmosphere | Newspaper headlines; romantic sunsets; increased birth rate |
| Source: J. D. Lissauer, Nature 402 (1998): C11–C14. |