SN 1181 belongs to a rare class of supernovas called Type Iax in which the thermonuclear flare-up could be the result of not one but two white dwarfs that have violently collided yet fail to detonate completely, leaving behind a “zombie star.”

On the morning of Feb. 23, 1987, a couple of dozen subatomic particles known as neutrinos zinged through specially instrumented underground sensors in Japan, Ohio and Russia.