The familiar script of planetary defence has been torn up. For decades, the globe's foremost space agencies operated under the assumption that the greatest threat to Earth came from within its own boundaries: asteroids and comets born in our solar system, following predictable, well-charted orbital paths.
That framework, however, is being dramatically tested by a terrifyingly fast and utterly unpredictable class of object: the interstellar visitor. These celestial tourists arrive from beyond our stellar neighbourhood, and they are forcing scientists and defence planners to confront a profound question: are Earth's protective systems truly prepared for a threat that doesn't play by our rules?
