  In this work we propose a novel campaign for constraining relativistically
compact MACHO dark matter, such as primordial black holes (PBHs), using the
moon as a detector. PBHs of about $10^{19} \textrm{ g}$ to $10^{22} \textrm{
g}$ may be sufficiently abundant to have collided with the moon in the history
of the solar system. We show that the crater profiles of a PBH collision differ
from traditional impactors and may be detectable in high resolution lunar
surface scans now available. Any candidates may serve as sites for in situ
measurements to identify high pressure phases of matter which may have formed
near the PBH during the encounter. While we primarily consider PBH dark matter,
the discussion generalises to the entire family of MACHO candidates with
relativistic compactness. Moreover, we focus on the Moon since it has been
studied well, but the same principles can be applied to other rocky bodies in
our solar system without an atmosphere.
