4 ms·
The point isn’t dimness. It’s resolution (well angular, the number of pixels also doesn’t matter that much). If you want to resolve things that are close togeth
by hnaccount_rng 5y ago
The point isn’t dimness. It’s resolution (well angular, the number of pixels also doesn’t matter that much). If you want to resolve things that are close together you physically can’t separate the signals. And what is too close depends inversely on the aperature, so yeah you really need the size, for some observations.
Fun fact for dimness: We are pretty much at “we can count every photon that comes” so if you want to pick up far away things, increasing the aperature is also one of the few things you can do. But at that point you’d probably prefer multiple telescopes if you can align them properly
- elihu 5y agoIs it just that infrared light doesn't focus as easily as visible light unless you scale up the size of the telescope accordingly? (For instance, at some point light stops behaving like light and starts behaving like radio waves.)
- hnaccount_rng 5y agoThe wave length of the photons also goes into it yes. I’d have to look up the precise formula. But it’s basically larger aperature -> smaller angle of separation. Longer wavelengths -> larger angle of separation. From a physics point of view there really isn’t much difference between light and radio waves. Both is just em radiation. But the absorption by matter (well really gas, there is nothing else) changes with wavelength too. And you’d optimize the ccds for whatever you want to look at. So that would be the primary consideration and keep in mind these things tend to also be build as tech demos (which also means you typically don’t get to realize all design capabilities in action). So “because it’s the most we could get away with” is a reasonable reason