Explain what is meant by the Rayleigh criterion for the resolution of two point sources.
An astronomical satellite is designed to observe in the far-ultraviolet range of 15 nm15\text{ nm}15 nm to 60 nm60\text{ nm}60 nm.
Explain why this instrument must be located in orbit outside Earth's atmosphere. Go on to discuss one advantage that this telescope has compared to a space telescope of the same primary mirror diameter that detects visible light.
Table 1 shows details of two proposed ground-based radio telescopes.
TelescopeDiameter / mDish ShapeTelescope Alpha120sphericalTelescope Beta40parabolic \begin{array}{c|c|c} \text{\bf Telescope} & \text{\bf Diameter / m} & \text{\bf Dish Shape} \\ \hline \text{Telescope Alpha} & 120 & \text{spherical} \\ \text{Telescope Beta} & 40 & \text{parabolic} \end{array} TelescopeTelescope AlphaTelescope BetaDiameter / m12040Dish ShapesphericalparabolicBoth telescopes detect radio signals at a key spectral wavelength of λ=6.0 cm\lambda = 6.0\text{ cm}λ=6.0 cm.
Compare the performances of Telescope Alpha and Telescope Beta when used to observe the same faint radio source. In your comparison, include a quantitative calculation of their relative collecting powers.
