I'm hoping someone can explain this to me like I've five. I'll make some assumptions and a conclusion here. Please tell me where I am wrong.
I think of the light coming from Jupiter as a non-stop stream of photons. Sort of like a hose pointed directly at my eyes. And that stream is essentially round - like the planet's facing surface. This stream is actually pointing out in all directions, but only the particles that are pointed directly towards my eye are the ones I see. The person standing next to me is getting their own stream and the two do not mix (i.e. we don't see the same particles).
Let's say that Jupiter is 40 arcseconds across. This defines the width of said stream and is essentially identical for me, the person next to me, my 4.5" scope and my 10" scope. So the diameter of mirror being directly struck seems like it would be the same. Yet the 10" scope is capturing more photons.
My initial guess was that the larger mirror had a higher 'resolution' (better construction) and was better able to resolve the stream. But further thinking leads me to believe that it has to do more with the curvature of the mirror. If I look directly down the tube, then the flow of photons would appear to be hitting the mirror in a circular fashion. Yet the concavity of a mirror means that the area being struck by photos is not circular, but oval-shaped, and that that shape itself is 'elongated' across the surface. The elongated oval is wider on the 10" (as the concavity is perhaps less pronounced) and thus has more area. This results in more photons captured.
Am I close?
Edited by nhanimator, 22 September 2021 - 05:57 AM.