If the distance from the Earth to the Moon is 38 108 m what

If the distance from the Earth to the Moon is 3.8 10⁸ m, what diameter would be required for a telescope objective to resolve a Moon crater 294 m in diameter? Assume a wavelength of 502 nm.

D= .....m

Solution

theta_min = 1.22*lambda/D.

Theta_min = 294/3.8x10^8 = 7.74 x 10^-7

and lambda = 502nm giving

D = 0.791 m. Another reason why telescopes are large.