Arguably, the entire history of classical astronomy is one big case of frequency analysis: people noticed the repeating patterns in the observable cosmos (ciphertext) to infer future positions of celestial bodies (the plaintext) and the relative period lengths to determine the relative positions of them all and our position/view direction within it (private key).
First, they noticed that light and dark cycle, and called those days. They noticed that moon phases and seasons cycle and came up with years and moon charts. They noticed “wanderers” like mars and venus, and the cycling of those observations led them to postulate future appearances and the kind of cosmos that would lead to our observations. And so on.
Arguably, the entire history of classical astronomy is one big case of frequency analysis: people noticed the repeating patterns in the observable cosmos (ciphertext) to infer future positions of celestial bodies (the plaintext) and the relative period lengths to determine the relative positions of them all and our position/view direction within it (private key).
First, they noticed that light and dark cycle, and called those days. They noticed that moon phases and seasons cycle and came up with years and moon charts. They noticed “wanderers” like mars and venus, and the cycling of those observations led them to postulate future appearances and the kind of cosmos that would lead to our observations. And so on.