There are lots of ways to describe how rarely neutrinos interact with normal matter. Duke’s Kate Scholberg, who works on them, provided yet another. A 10 Mega-electron Volt gamma ray will, on average, go through 20 centimeters of carbon before it’s absorbed; a 10 MeV neutrino will go a light year. “It’s called the weak interaction for a reason,” she quipped, referring to the weak-force-generated processes that produce and absorb these particles.

But there’s one type of event that produces so many of these elusive particles that we can’t miss it: a core-collapse supernova, which occurs when a star can no longer produce enough energy to counteract the pull of gravity. We typically spot these through the copious amounts of light they produce, but in energetic terms, that’s just a rounding error: Scholberg said that 99 percent of the gravitational energy of the supernova goes into producing neutrinos.

Within instants of the start of the collapse, gravity forces electrons and protons to fuse, producing neutrons and releasing neutrinos. While the energy that goes into producing light gets held up by complicated interactions with the outer shells of the collapsing star, neutrinos pass right through any intervening matter. Most of them do, at least; there are so many produced that their rare interactions collectively matter, though our supernova models haven’t quite settled on how yet.