A flash of luck helped astronomers solve a cosmic mystery: What causes powerful but fleeting radio bursts that zip and zigzag through the universe? Scientists have known about these energetic pulses — called fast radio bursts — for about 13 years and have seen them coming from outside our galaxy, which makes it harder to trace them back to what's causing them. Then this April, a rare but considerably weaker burst coming from inside our own Milky Way galaxy was spotted by two dissimilar telescopes: one a California doctoral student’s set of handmade antenna s, which included actual cake pans, the other a $20 million Canadian observatory.