A telescope has an objective mirror of 6m. An astronomer uses it to determine if a certain object is a binary star, i.e. two stars in orbit around a common point. If the object is 25 light years away (a light year is the distance light travels in one year) what is the minimum separation of the two stars if they can just be resolved? The only notes I have about resolution were taken in class about satellite cameras. In that case, would: d_min = h(lambda)/(a) still apply? d_min is minimum separation between the 2 objects, h would be the distance from the stars to the telescope, but what value would lambda be? The wavelength of light? And would 'a' be the area of the mirror? Does the fact that it's an objective mirror change anything? Or would this apply only to a lens?