More often than not, astronomers have a specific something they’re looking for when searching the cosmos. But the universe is achingly huge and mysterious, leading to discoveries no one ever set out to find.

These unexpected catches often end up being way cooler and more significant than what astronomers intended to explore. Here are ten of our favorite “accidental” cosmic discoveries—unintentional findings that nevertheless contributed greatly to our understanding of the universe.

1. Uranus (1781)

In the spring of 1781, British astronomer William Herschel found a faint, sluggish object in the constellation Gemini. At first, Herschel, who was cataloguing stars at the time, was convinced that the object was a comet. Follow-up observations revealed that it had moved across the sky, and

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