how do telescopes work? why does a bigger mirror mean deeper images? how can we focus a telescope on a specific point in the sky?

Question

i understand how light and photography works, but it baffles me how telescopes can be so precise, and how they can ”collect” light from so far away. Idk please help me understand them a bit better

In: 5

Answer 1

A bigger primary mirror means more light is collected. This lets us see dimmer objects, and the further away something is the dimmer it appears.

Additionally a larger mirror allows us to distinguish smaller features; large telescopes have better angular resolution. This is because of diffraction and is beyond my ability to explain. Suffice to say it is a fundamental property of light. The further away something is the less of the sky it takes up, so the better the resolution you need to see useful things about it.

They focus on a particular point on the sky by moving to look at that point. Imagine a very zoomed in camera that you point at the region of interest. They are focused at infinity because that is where the stars, galaxies etc are (sort of).