Simple Optic Resolution Problem/ Rayleigh's Criterion

[bmb2009]

Homework Statement

Suppose you wanted to be able to see astronauts on the moon. What is the smallest diameter of the objective lens required to resolve a 0.68 m object on the moon?

Homework Equations

I was told to use Rayleigh's Criterion but i do not see how to relate the equation
θmin = 1.22λ/D where theta is the minimum resolvable angle, lambda is the wavelength and D is diameter?

The Attempt at a Solution

Didn't even know where to start, any help would be greatly appreciated! thanks

 

[haruspex]

How far away is the moon? What angle would a 0.68m wide object on the moon subtend at the telescope on Earth? What wavelength would be appropriate?