  Short period planets are subject to intense energetic irradiations from their
stars. It has been shown that this can lead to significant atmospheric
mass-loss and create smaller mass planets. Here, we analyse whether the
evaporation mechanism can affect the orbit of planets. The orbital evolution of
a planet undergoing evaporation is derived analytically in a very general way.
Analytical results are then compared with the period distribution of two
classes of inner exoplanets: Jupiter-mass planets and Neptune-mass planets.
These two populations have a very distinct period distribution, with a
probability lower than 10^-4 that they were derived from the same parent
distribution. We show that mass ejection can generate significant migration
with an increase of orbital period that matches very well the difference of
distribution of the two populations. This would happen if the evaporation
emanates from above the hottest region of planet surface. Thus, migration
induced by evaporation is an important mechanism that cannot be neglected.
