  We introduce a new invariant, the coronal of a graph, and use it to compute
the spectrum of the corona $G\circ H$ of two graphs $G$ and $H$. In particular,
we show that this spectrum is completely determined by the spectra of $G$ and
$H$ and the coronal of $H$. Previous work has computed the spectrum of a corona
only in the case that $H$ is regular. We then explicitly compute the coronals
for several families of graphs, including regular graphs, complete $n$-partite
graphs, and paths. Finally, we use the corona construction to generate many
infinite families of pairs of cospectral graphs.
