Astronomers have discovered a galaxy so unlike anything in the textbooks that the researcher who found it, after 25 years studying these objects, says he has never seen its equal. Named RAD-BAARG, it is falling supersonically into a distant cluster of galaxies and ploughing up a glowing arc of radio plasma nearly 1.8 million light years across, shaped uncannily like a bow and arrow. It offers astronomers their clearest view yet of a bow shock, a structure long predicted but almost never glimpsed. And in a final twist, the first person to spot it was not a professional at all, but a student combing through telescope data from a remote hillside in the Himalayas.