  The supermassive black hole candidates at the center of every normal galaxy
might be wormholes created in the early Universe and connecting either two
different regions of our Universe or two different universes in a Multiverse
model. Indeed, the origin of these supermassive objects is not well understood,
topological non-trivial structures like wormholes are allowed both in general
relativity and in alternative theories of gravity, and current observations
cannot rule out such a possibility. In a few years, the VLTI instrument GRAVITY
will have the capability to image blobs of plasma orbiting near the innermost
stable circular orbit of SgrA$^*$, the supermassive black hole candidate in the
Milky Way. The secondary image of a hot spot orbiting around a wormhole is
substantially different from that of a hot spot around a black hole, because
the photon capture sphere of the wormhole is much smaller. The radius of the
photon capture sphere is independent of the hot spot model, and therefore its
possible detection, which is observationally challenging but not out of reach,
can unambiguously test if the center of our Galaxy harbors a wormhole rather
than a black hole.
