The universe is vast, but occasionally, something truly alien slips through our cosmic neighbourhood, offering a fleeting glimpse into the ancient building blocks of other star systems. This is precisely the case with the interstellar comet 3I/ATLAS, a colossal, fast-moving space rock that has now done something rather extraordinary: it has started turning vivid green.
Astronomers have been scrambling to track this mysterious visitor, only the third confirmed interstellar object (1I/'Oumuamua and 2I/Borisov were the first two) ever detected passing through our solar system. Discovered back in late June, the comet is screaming through space on a hyperbolic, U-shaped path that confirms it is not gravitationally bound to our sun — it is merely passing by at an estimated 210,000 kilometres per hour (130,000 mph) before heading back out into the void, never to return.
