2. Data and methods To reveal the effect mentioned above, the mean daily velocities were analyzed by the superimposed epoch method for 54 periods of inferior conjunctions in 1995–2012. The superimposed epoch method (or the “synchronous detection”) is based on the separation of the time interval under consideration into the equal subintervals of the specified duration T; and then the observational data in the same temporal points from the beginning of the above-mentioned subintervals are summed up or averaged. As a result, if the data vary with T or a comparable period, the corresponding effect is accumulated; while the data varying in time randomly or with the periods incomparable with T are smoothed out. The instants of the superior conjunctions were refined by using the HORIZONS software (http://ssd.jpl.nasa.gov/horizons.cgi). The mean daily velocities were derived from the mean hourly ones, which were measured by ACE satellite in L1 Lagrangian point (ACE, 2013), i.e. in the point of gravitational equilibrium between the Earth and the Sun, at the distance of approximately 1.4 million kilometers from the Earth. A few particular examples of variations in the mean daily velocities during the inferior conjunctions of Mercury are given in Fig. 1. At last, let us mention that differences in the space weather and in the relative positions of the planets and the Sun above ecliptic and with respect to the perihelion of her mean orbit were not taken into account yet in our analysis, although their role might be noticeable.