For the first time, scientists have tracked the source of a "fast radio burst" - a fleeting explosion of radio waves which, in this case, came from a galaxy six billion light-years away.
The cause of the big flash, only the seventeenth ever detected, remains a puzzle, but spotting a host galaxy is a key moment in the study of such bursts.
It also allowed the team to measure how much matter got in the way of the waves and thus to "weigh the Universe".
Their findings are published
in Nature.
