What is the Difference Between a Reflecting Telescope and Refracting Telescope?

Draw a labelled ray diagram of an astronomical telescope in the near point adjustment position.

A giant refracting telescope at an observatory has an objective lens of focal length $15 \mathrm{m}$ and an eyepiece of focal length $1.0 \mathrm{cm}$. If this telescope is used to view the Moon, find the diameter of the image of the Moon formed by the objective lens. The diameter of the Moon is $3.48\times {10}^6 \mathrm{m}$, and the radius of the lunar orbit is $3.8\times {10}^8 \mathrm{m}$.

Draw a levelled ray diagram showing the image formation in an astronomical telescope. Define its magnifying power and write expression for it.

Draw the schematic diagram of a Cassegrain telescope.