In the constellation Centaurus, some 340 light-years from Earth, astronomers have detected what may be the first confirmed moon beyond our solar system — a Jupiter-sized body orbiting not a star, but a brown dwarf, that strange cosmic in-between object too massive to be a planet yet too dim to be a star. The discovery, made through the subtle gravitational wobbles of the brown dwarf itself, does not merely add a new entry to the catalog of known worlds; it quietly dismantles the vocabulary we have long used to describe them. When the familiar categories of 'planet' and 'moon' no longer hold, s