Summary
A supernova within about 160 light-years, or 1.5 quadrillion kilometers, would qualify. On a galactic scale, it’s in our immediate neighborhood. Supernovas are fairly rare, occurring roughly once per century in a large galaxy like our Milky Way.
The iron 60 peak in ocean sediments is created when massive stars explode. The material spent about 200,000 years coasting through interstellar space before it fell to Earth. Two supernovas may have contributed to the most recent peak, with one exploding 2.3 million years ago.
Lucy, nicknamed Lucy, walked on Earth about three million years ago. She may have missed that particular event, but if so, her descendants may have gazed up into the sky. And here we are, millions of years later, still wondering over the same thing.
