How Did We Misunderstand Galaxies For So Long_ _ Boring Science for Sleep
Close your eyes and consider a quiet, unsettling truth: for most of human history, we thought our galaxy was the entire universe. Every star you could see, every faint smudge of light—we assumed that was everything that existed [citation:3]. We now know that assumption was wrong by a margin so large it's almost embarrassing. The observable universe contains an estimated two trillion galaxies [citation:3]. But what's truly unsettling is that we spent most of the 20th century unable to correctly map the shape, size, and structure of our own galaxy—the one we are literally standing inside of…
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