From Earth's standpoint, planets periodically reverse their direction. We call this a retrograde period. It is a time to assimilate that planet's energies, to bring them home to us and work with them on inner levels. We call this a station.
Energy is very pronounced then, and events on earth reflect that emphasis.
During the few days around the directional change of a planet, its action manifests more strongly. We can see its principle more clearly then. Pay attention to the station days. They're always significant. Mercury has two stations this month.