In 2017 a telescope in Hawaii caught something that had come from another star — the first interstellar object ever seen inside our solar system. It was the wrong shape, it tumbled strangely, and as it left it accelerated with no visible comet tail, which is where a Harvard astronomer said the quiet part out loud: what if it was built?
A clean documentary primer on the discovery, the frantic scramble to observe it before it vanished, and why nothing about it fit the catalog.
The evidentiary spine: the extreme elongation, the reddish surface, the tumbling light-curve, and the non-gravitational acceleration that started every argument.
NASA's own file on the object: a cigar- or pancake-shaped body up to a quarter-mile long, and the estimate that such visitors slip through the inner solar system roughly once a year.
The rigorous physics view: how you eject an object from a distant star system, and what its weird motion actually tells us about where it was born.
The interview that split the field: Harvard's Avi Loeb argues the simplest fit for the acceleration is a thin artificial light-sail — and accuses his colleagues of looking away.
Loeb himself lays out the case at length: why he thinks a technological origin deserves a seat at the table, and why 'natural but unexplained' isn't a free pass.
The sober counter-case: nitrogen icebergs, hydrogen icebergs, and cosmic dust bunnies — a tour of the mundane explanations that still haven't fully closed the file.