(a)[2]
Define the radian in words.
(b(i))[2]
The Moon is about $3.8 \times 10^{5}\,\text{km}$ away from Earth. Estimate the least diameter of a circular crater on the Moon’s surface that the telescope can detect.
(b(ii))[2]
Suggest why craters with the same diameter as the one calculated in (i), but on the surface of Mars, are not visible with this telescope.