Supernovas happen thousands of light-years, so they don't affect us. Or that's what we thought until the geoscientist at Robert Brakenridge University Colorado Boulder looked at the rings of the logs.

The rings are excellent natural historical records and Brakenridge noted that the concentration of radiocarbon in the ring increases when a subernova is produced. Although no concrete conclusion can be reached yet, it has opened the way for research into the impact of this phenomenon.