  A shadow of the moon, with a statistical significance of $5\sigma$, has been
observed in the underground muon flux at a depth of 2090 mwe using the Soudan 2
detector. The angular resolution of the detector is well described by a
Gaussian with $\sigma \le 0.3^{\circ}$. The position of the shadow confirms the
alignment of the detector to better than $0.15^{\circ}$. This alignment has
remained stable during 10 years of data taking from 1989 through 1998.
