An astronomer observed Mars at opposition using a telescope that has a lens 50 cm (20 inch...

An astronomer observed Mars at opposition using a telescope that has a lens 50 cm (20 inches) in diameter. The astronomer observes in visible light at a wavelength of 500 nanometers. What is the smallest feature the astronomer could resolve on Mars if the image were not affected by seeing? How does this compare to the diameter of Mars? To the diameter of Olympus Mons? (Use the equation for angular resolution, Equation 6.6.)

Equation 6.6 Resolution Equation 6.6 can be used to calculate the smallest resolvable features that can be seen with a telescope of a given diameter operating at a given wavelength. For example, what is the minimum angle that can be resolved using a telescope with a diameter, D = 2 m, at a wavelength, λ = 5 × 10−7 m? Using these values for D and λ in Equation 6.6, we get

This is about 1⁄30,000 as large as the angular size of the Sun or Moon.