Question

A commonly asked question is "Which telescope is the most powerful?" Con sider the following three telescopes, all working a wavelength of 1 micron: » A 10-meter telescope with focal ratio 15. » An interferometer composed of two 1-meter telescopes separated by 330 meters. » A 2.5-meter telescope with focal ratio 5 Each of these telescopes has different strengths. Which of them would be best suited for accomplishing each of the following observational tasks? Why? (a) Resolving the diameter of a nearby star (b) Surveying a very large area of the sky quickly (c) Measuring the spectrum of a faint distant galaxy

Answer 1

a-Resolving the diameter of a neighbouring star- A 10 M telescope with focal ratio 15 because higher is the focal ratio , less is the area of vision , so for observing a single star, a telescope with focal ratio 15 is best.

b-Surveying a very large area of sky quickly-A 2.5 M telescope with focal ratio 5 because ,lower is the focal ratio ,wider is the view.

c-Measuring the spectrum of faint distant galaxies-The inferometer because they can produce images of distant galaxies with the angular resolution of a HUGE telescope.