  Exomoons are expected to produce potentially detectable transit timing
variations (TTVs) upon their parent planet. Unfortunately, distinguishing
moon-induced TTVs from other sources, in particular planet-planet interactions,
has severely impeded its usefulness as a tool for identifying exomoon
candidates. A key feature of exomoon TTVs is that they will always be
undersampled, due to the simple fact that we can only observe the TTVs once per
transit/planetary period. We show that it is possible to analytically express
the aliased TTV periodicity as a function of planet and moon period. Further,
we show that inverting an aliased TTV period back to a true moon period is
fraught with hundreds of harmonic modes. However, a unique aspect of these TTV
aliases is that they are predicted to occur at consistently short periods,
irrespective of what model one assumes for the underlying moon population.
Specifically, 50% of all exomoons are expected to induce TTVs with a period
between 2 to 4 cycles, a range that planet-planet interactions rarely manifest
at. This provides an exciting and simple tool for quickly identifying exomoons
candidates and brings the TTV method back to the fore as an exomoon hunting
strategy. Applying this method to the candidate, Kepler-1625b i, reveals that
its TTV periodicity centers around the median period expected for exomoons.
