"As matter expands away from the blast site, it thins out, so by the time the ejecta from a nearby supernova reaches Earth, perhaps a few hundred metric tons mi

"As matter expands away from the blast site, it thins out, so by the time the ejecta from a nearby supernova reaches Earth, perhaps a few hundred metric tons might rain upon our planet over a length of time. That might sound like a lot, but about that same amount of meteoric material slams into our atmosphere every day. So supernovas aren’t appreciably adding to Earth’s weight, nor are they a big danger to us in this way."