>>935819445 (OP)well: option 1:
You can look up and see some bright stars.
you then go and look through a $100 telescope and its able to look at a small area of that view and resolve the basic blurry shapes of the Andromeda galaxy, and resolve the same individual distant stars.
your local $10million observatory with a telescope the size of a truck can image the exact same view, and suddenly can pick out details and some structure in the exact same galaxy area, and spots more of the fainter little stars
your $1.5 billion dollar mega-structure telescope on top of a mountain in the Atacama desert can then resolve the exact same view, and starts spotting all the little distant galaxies in the background, as little blurry parts.
and then you blow 10+ billion-dollars on a space telescope sitting at a lagrange point, and bingo, you're seeing all those galaxies which are impossible to see by the naked eye.
OR:
Option 2: the earth is flat, and its all a CONSPIRACY by Nasa to hide the shape of the world, and the moon landings were "CGI" (in 1969, when the most advanced CGI in the world was able to draw a stick-man...) and its all in fact not real.
If you take option 2, you're a fucking moron.
the plain, simple fact is, yes, it is real.
The only part which is not 100% definitely real, is explanations or models of some of the little details of how those galaxies formed or similar stuff, because the explanations are based on available data, and each time a new, better, bigger telescope is invented, we can see more detail, and discover that often what had been assumed about something wasn't in fact correct.
what does not happen is modern scientists getting a new telescope and go "oh, that entire galaxy doesn't exist"
You occasionally got that sort of radical re-evaluation of objects in the past, when the biggest telescopes in the world were smaller than that 10 million dollar observatory. But as technology has improved, that becomes increasingly unlikely to happen.