Impact craters form when an impactor – like an asteroid or comet – hits the target surface of a planet or moon.
The impact occurs at high speed, and the final crater depth, diameter, and shape are effectively determined by the surface gravity, the mass of the impactor, and the velocity of the impactor.
Crater-count dating seems perfectly logical: the more craters, the older the landscape.
It assumes, however, that impactors arrive at a roughly steady rate and produce one crater per hit.
They urged a high degree of caution, therefore, when trying to infer the age of a planetary surface.
The abstract states: The small crater populations (diameter smaller than 1 km) are widely used to date planetary surfaces.
Note: There are craters of other origins, such as pit craters or caldera craters at the top of volcanoes.A single large impact can produce a million secondary craters, blurring relationships between crater counts and the age of a surface.Astronomers had hoped that secondaries could be identified, thereby alleviating the confusion.Only impact craters are used to date surfaces, and for brevity I will only be referring to them from this point on as “craters” instead of “impact craters.” The basic idea behind using craters as an indicator of a surface’s age is that the longer the surface is around, the more craters will form.Worries about the crater count dating method, widely relied upon to infer ages of planetary surfaces, began emerging in 2005.