Start Dating craters

Dating craters

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.

A single large impact can produce a million secondary craters, blurring relationships between crater counts and the age of a surface.

Worries about the crater count dating method, widely relied upon to infer ages of planetary surfaces, began emerging in 2005.

Those worries have not subsided; they have only grown worse. We’ve kept track of the crater count crisis since 2005, when the problem of secondary craters was brought to light (10/20/2005, 6/08/2006, 9/25/2007, 3/25/2008, 7/25/2010).

They compared a series of before and after shots, and discovered 222 new craters had formed.

This led to a new estimate, that says 180 craters of at least ten metres in diameter form each year, according to an accompanying News and Views article in This is partly down to the team recognising surface reflectance zones of the craters that were wider than recorded.

Note: There are craters of other origins, such as pit craters or caldera craters at the top of volcanoes.

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.

The purpose of that mission is to ensure any future Moon explorers have a better idea of what to expect on the surface, and where to set up their fuelling stations for Martian missions. The LRO has caught on camera incidents such as a March 2013 collision, when a small boulder hit the Moon at such force it emitted a flash of light ten times brighter than anything ever recorded.