2

It depends. In some areas, far-away stuff is obscured by obstacles in the foreground. In other places, we can see almost all the way to the earliest (and furthest-away) galaxies, like in the Hubble Deep Field image: The very earliest objects have so much redshift they disappear out of view for visible-light telescopes. That's where the JWST comes in: ...


1

As far as microlensing is concerned: Not likely This is a bit of a dodge on the question, but it is hard to come up with a scenario where microlensing becomes the dominant PSF term. Microlensing occurs during conjunction with a stellar or planetary object, and results in a momentary (seconds-to-days timescale) increase in the brightness of the observed ...


Only top voted, non community-wiki answers of a minimum length are eligible