[frabjoused]

If light is hitting it, can you explain why not?

[thrtythreeforty]

The naïve optical instrument will be diffraction limited. The resolving power of a lens, basically how "sharp" the resulting image will be, goes down as you decrease the size of the aperture relative to the focal length (that is, as the f-stop number goes up).

A telescope that could zoom into an exoplanet would have an f value of a kajillion or so.

[stouset]

You’d need a 90km aperture to get a one pixel image of an Earth-sized exoplanet at 100ly.

[recursive]

I don't know much about it, but my guess is that 0* photons from that planet make their way into any given telescope lens in a given day.