Number of impacts

A very important question about impacts
is: how many impacts happen and how many years pass between two
impacts (in other words, with which frequency do they happen?)

About this question, it is necessary to say
that from the study of craters around the solar system,
scientists have deduced that after a period of intense
bombardment in the inner solar system that ended about 3.9 bilion
years ago (see the history of the solar system), cratering
appears to have continued at a slower, but fairly unifom rate
untill today.

To give a first estimation of this odiern
frequency for what concerns Earth, two values are needed: it is
first of all necessary to know how many Neos
of different dimensions surround the Earth and, in a second
moment it is necessary to determine the probability
of impact by a single object of a given dimension.

Once this two values are known, it is
possible to represent the estimated frequency of impacts on Earth
as a function of the energy of the impact event

This image represents the
estimated frequency of impacts on Earth as a function of
their energy . It is important to understand that this graph only represents a statistical estimation. For example: an event as the KT impact (click here to know more) is estimated to happen every
mean period of 100 million years. This doesn't mean that
exactly every 100 million years such an event will
happen! |