..that the lead-time is inversely proportional to the reciprocal of the square of the distance of the object as viewed from arms length in comparison to the size of a hole in a polo mint...or some such formula.
i.e. bigger = more time (I would hope)
PS. The polo-mint inverse square reciprocal law does yield an SI unit (the 'Polo') but was rejected due to trademark infringement.
Todays meteor would have a value of 0.02 Polos (at a guess), with a value of >0.5 polos being one to worry about :-)
Larger meteors being measured in 'Donuts', where 1 donut = 375.2 polos (due to the squaring rule and the variance in sugar coating).
I believe the dinosaurs were wiped out by a donut-meteor.
It feels like Monday to me....sorry.