The moment he saw the brilliant light captured by his camera, “it all clicked” for Victor Buso: All the times his parents woke him before sunrise to gaze at the stars, all the energy he had poured into constructing an observatory atop his home, all the hours he had spent trying to parse meaning from the dim glow of distant suns. “In many moments you search and ask yourself, why do I do this?” Buso said via email. This was why: Buso, a self-taught astronomer, had just witnessed the surge of light at the birth of a supernova — something...