A nearby supernova (SN) explosion in the past can be confirmed by the detection of radioisotopes on Earth that were produced and ejected by the SN. We have now measured a well resolved time profile of the ${}^{60}\mathrm{F}\mathrm{e}$ concentration in a deep-sea ferromanganese crust and found a highly significant increase 2.8 Myr ago. The amount of ${}^{60}\mathrm{F}\mathrm{e}$ is compatible with the deposition of ejecta from a SN at a distance of a few 10 pc. The well defined time of the SN explosion makes it possible to search for plausible correlations with other events in Earth’s history.

• Received 18 February 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.171103