Dark Matter

When did we start to realize that we actually didn't know what most of the universe was made of? Cause there must have been until relatively recently, certainly within the last century. Did fritz vicke come up with the idea of the name dark matter? It sort of developed. I mean, he was the first to to study, i mean, the other, the other famous example is vera reuben. She looked at individual galaxies and measured how fast they were spinning. And as that was another key piece of evidence for her swesa sir explaining very quickly, how you measure the rotation rate of a galaxy. This is te ema o asa oin oa, g