Love the premise and I see several years are posted. I like your philosophy of science section especially, because while most would neglect that area, it's probably got good predictive/foreshadowing juice in general (although not necessarily for any given year).

Skimming https://en.wikipedia.org/wiki/1875_in_science the twin studies and behavioural genetics is interesting. The challenger-deep thing too since it's earlier than I would have guessed, but IMHO it would be more exciting/appropriate to categorize as "exploration" than science. Did they publish a "paper" about stuff like that back then, or just tell the royal society, tell the newspapers and call it good?

A pointless but fun question to think about is, how to decide the most important thing that happened in a given year? Sometimes a discovery, sometimes an idea, sometimes a project, election, or war. But for a slow year.. maybe it's just that someone who will have that idea or start that project later was born.