PLANET VS CRATER SIZE
|SOLAR SYSTEM BODY||DIAMETER km||GRAVITY||ESCAPE VELOSITY||BASINS km||PEAK RING km||COMPLEX km||SIMPLE km||REFERENCE|
|MERCURY||4,880||0.38||4.2 km/s||>~400||~110 – ~400||10 – 110||<~10||Greeley 2011|
|VENUS||12,104||0.91||10.4 km/s||–||>50 – 60||10 – ~50||<10 – 20||Greeley 2011|
|EARTH||12,756||1||11.2 km/s||>100||~30 – ~100||5 – ~30||<5||Grieve 2006|
|EARTH’S MOON||3,476||0.17||2.38 km/s||>220||175 – 220||30 – 175||<30||Wood 2003|
|MARS||6,788||0.38||5.0 km/s||~200||~20||~2.6||Greeley 2011|
The primary factors governing the size and shape of impact craters are the impact energy, gravity and properties of the target. Gravity affects the cratering process by influencing the dimensions of the excavation bowl, the extent of the ejecta and various post-impact crater modifications. In the modification stages of impact cratering, gravity influences the degree of slumping, perhaps governing the size of potential central uplifts (Greeley 2011).
The Earth is immersed in a swarm of Near Earth Asteroids (NEAs) capable of colliding with our planet, a fact that has become widely recognized within the past decade. The first comprehensive modern analysis of the impact hazard resulted from a NASA study requested by the United States Congress. This Spaceguard Survey Report (Morrison 1992) provided a quantitative estimate of the impact hazard as a function of impactor size (or energy) and advocated a strategy to deal with such a threat (Morrison, 2007).
Greeley, R. 2011, Planetary Geomorphology, Cambridge.
Grieve, R.A.F. 2006, Impact Structures in Canada, Geological Association of Canada.
Morrison, D. 2007 The Impact Hazard: Advanced NEO Surveys and Societal Responses, Comet/Asteroid Impacts and Human Society 2007, pp 163-173
Wood, C.A. 2003, The Modern Moon, Sky Publishing