# Estimate what size details could be observed on the surface of Mars during the great opposition of 2003 (radius of Mars 3,400 km)

**Estimate what size details could be observed on the surface of Mars during the great opposition of 2003 (radius of Mars 3,400 km) with a telescope with a diameter of 200 mm.**

Let us determine the theoretical resolution of the telescope: β = 1.22 * λ / D – the resolution of a telescope with a diameter D at a wavelength λ. Substituting λ = 0.55 µm (maximum eye sensitivity), we get the formula β = 140 ”/ D (students who immediately wrote this formula were not penalized). Those. for a telescope from the condition of the problem β = 0. ”7.

During the great opposition, the distance to Mars is less than 60 million km. The angular size of Mars will be 2 * 3400/60000000 * 206265 = 24 ”(students who immediately wrote this value were not fined).

The linear size on Mars, corresponding to the resolution of the telescope (0. ”7) – 0.7 / 24 * 6800≈200 km. Details of this size were observed to the limit on the surface of Mars in August 2003 with a 200 mm telescope (often the atmosphere limits the resolution to 1–2 ”).