|-Lew Thomas 4-28-01|
First we shall apply Dawes Limit, which strictly applies to the resolution of two equally bright points of light. This is
R” = 4.56/D (1)
D = the diameter of the telescope objective in inches
R” = the resolving power in seconds of arc.
The mean distance of the Moon from Earth is 384,500 km. Therefore, the linear dimension of any object on its surface is
R = rq (2)
r = the distance to the Moon = 384,500 km.
q = the angle of the Moon object subtended at the Earth observer in radians
R = the linear dimension of the Moon object in km.
Combining (1) and (2), we have
R = r 4.56p/(3600×180 D)
R = 8.5003/D (3)
Using this relationship and assuming a perfect telescope, the following table is constructed
|OBJECTIVE DIAMETER||MINIMUM DISCERNABLE CRATER|
|Unaided eye (0.1 in.)||85|