Two radio telescopes are used in a special technique called

Two radio telescopes are used in a special technique called long-baseline interferometry, which causes the two to act as a single telescope with an effective diameter of 100 mi. At what distance from this telescope would two objects 250 000 mi apart be at the limit of resolution? Assume that the wavelength of the radio waves from these objects is about 1.00m.

Solution

resolving power

1.22*lemda/a = d/D

=> D = 1000*1609/1)*( 25000*(1609/1))/(1.22*1)

=> D = 5.3*10^14 m