  The current exoplanet database includes 5454 confirmed planets and candidate
planets observed with the KEPLER mission. We find 932 planet pairs from which
we extract distance and orbital period ratios. While earlier studies used the
Titius-Bode law or a generalized version with logarithmic spacing, which both
lack a physical model, we employ here the theory of harmonic orbit resonances,
which contains quantized ratios instead, to explain the observed planet
distance ratios and to predict undetected exoplanets. We find that the most
prevailing harmonic ratios are (2:1), (3:2), and (5:3), in 73\% of the cases,
while alternative harmonic ratios of (5:4), (4:3), (5:2), (3:1) occur in 27\%
of the other cases. Our orbital predictions includes 171 exoplanets, 2 Jupiter
moons, one Saturn moon, 3 Uranus moons, and 4 Neptune moons. The accuracy of
the predicted planet distances amounts to a few percent, which fits the data
significantly better than the Titius-Bode law or a logarithmic spacing. This
information may be useful for targeted exoplanet searches with Kepler data and
to estimate the number of live-carrying planets in habitable zones.
