For decades it has been thought that a shock wave from a
supernova explosion triggered the formation of our Solar System.
According to this theory, the shock wave also injected material
from the exploding star into a cloud of dust and gas, and the
newly polluted cloud collapsed to form the Sun and its
surrounding planets. Traces of the supernova’s pollution can be
found in meteorites in the form of short-lived radioactive
isotopes, or SLRIs. SLRIs—versions of elements with the same
number of protons, but a different number of neutrons—found in
primitive meteorites decay on time scales of millions of years
and turn into different, so-called daughter, elements. A million
years may sound like a long time, but it is actually considered
short when compared to other radioactive isotopes studied by
geochemists and cosmochemists, which have half-lives measured in
billions of years. New work from the Carnegie Institute’s Alan
Boss and Sandra Keiser provides the first fully three-
dimensional (3-D) models for how this p