(Starts With A Bang!) – Ethan Siegel:
From the 1600s, Kepler’s and Newton’s Laws described planetary motion precisely. In 1781, Uranus’s discovery gave us a new testing ground. After multiple decades, something was clearly amiss. Uranus initially moved quicker than predicted, then as anticipated, and finally, too slowly. A spectacular possible explanation arose: a massive, additional, outer planet. …
Gravitation, all on its own, can reveal what’s present in the cosmos like nothing else. …
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