Diameter of telescope needed to resolve 3 m lunar lander

[twinkle24]

studying for exam- telescope problem (help!)

Homework Statement

What diameter optical telescope on the Earth would you need to resolve a lunar lander 3 m across on the surface of the moon 3.8e8m away?

Homework Equations

The Attempt at a Solution

the only thing I can think of is to use theta=1.22lamda/d... but what do I do with it? help!

 

[Stonebridge]

You need to assume a typical value for lambda. A wavelength in the visible spectrum.
d is the diameter you need to calculate.
theta is the angular separation of two points that can just be resolved.
What is the angular separation of those two points on the moon?

 

[twinkle24]

oh! that makes sense. so is the angular separation the size of the lander divided by the distance to it?

 

[Stonebridge]

That should work fine.

(Welcome to Physics Forums, by the way)

 

[twinkle24]

yay! thank you!