The top 5 astronomical discoveries of all time (so far)

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We’ve managed to discover quite a lot about our Universe from our relatively limited vantage point here on Earth. Many of those discoveries have been worthy of nothing more than an updated entry in some catalog. But some have been deeply revolutionary, completely changing the way we view the cosmos and our relationship to it.

What follows is a list of what I, a theoretical cosmologist, believe to be the most impactful discoveries ever made in astronomy. To help winnow down the possibilities to a manageable top-five ranking, I had to concoct some criteria. First, we're looking at discoveries that are both broad and deep (in the scientific sense), findings that simultaneously reached further than any previous discovery and also enabled (or at least accelerated) a new paradigm or branch of astronomy.

Second, I want to emphasize discoveries that were not obvious and didn’t just need someone to build a big enough telescope or powerful enough computer. I want discoveries that needed radical leaps of intuition and science-minded daring—where an enterprising scientist went out on a limb and followed their curiosity wherever it led.