Can all cosmological observations be accurately interpreted with a
  unique geometry?
  The recent analysis of the Planck results reveals a tension between the best
fits for ({\Omega}m0, H0) derived from the cosmic microwave background or
baryonic acoustic oscillations on the one hand, and the Hubble diagram on the
other hand. These observations probe the universe on very different scales
since they involve light beams of very different angular sizes; hence the
tension between them may indicate that they should not be interpreted the same
way. More precisely, this Letter questions the accuracy of using only the
(perturbed) Friedmann-Lema\^itre geometry to interpret all the cosmological
observations, regardless of their angular or spatial resolution. We show that
using an inhomogeneous "Swiss-cheese" model to interpret the Hubble diagram
allows to reconcile it with the Planck results. Such an approach does not
require us to invoke new physics nor to violate the Copernican principle.
