“These astronomical glass plates made history”

A very short but fascinating discussion, using pivotal photographs, of some of the most important developments in the history of astronomy:

http://nautil.us/issue/32/space/these-astronomical-glass-plates-made-history

I saw the observatories atop Mount Wilson virtually every day of my life until I went away for college.  And my parents took me to visit the observatory at Mount Palomar when I was still a child.  It was only years later that I really began to comprehend their significance for the history of science.