The Poisson distribution is a discrete probability distribution that expresses the probability of a given
number of events occurring in a fixed interval of time and/or space if these events occur with a known
average rate and independently of the time since the last event. (The Poisson distribution can also be used
for the number of events in other specified intervals such as distance, area or volume.) Distribution of
number of points in random point process under certain simple assumptions. Approximation to the binomial
distribution when aCount is large and aProbability is small. aLambda = aCount * aProbability.