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In the latest Gaia third data release one can find extremely small propermotion components for the star HD 7977. This, together with the radial velocitymeasurement lead to the conclusion that this star passed very close to the Sunin the recent past. Such a very close approach of a one solar mass star mustresult in noticeable changes in the motion of all Solar System bodies,especially those on less tight orbits, namely long-period comets (LPCs) andKuiper belt objects. We estimate and present these effects. Our currentknowledge on the stellar surroundings of the Sun found in the latest Gaiacatalogues allowed us to perform numerical integrations and prepare a list ofpotential stellar perturbers of LPCs. We use this list, made available in theStePPeD database. To study the past motion of LPCs under the simultaneousaction of the Galactic potential and passing stars, we use precise originalcometary orbits taken from the current CODE catalogue. We examine thereliability of the extremely small proper motion of HD 7977 concluding thatthis star can be an unresolved binary but according to the astrometry coveringmore than a century, the current Gaia results cannot be ruled out. We presentthe parameters of a very close passage of this star near the Sun. We also showexamples of the strong influence of this passage on the past motion of someLPCs. We also discuss the possible influence of this perturber on other SolarSystem bodies. It is possible that 2.47 Myr ago the one solar mass star HD 7977passed as close as one thousand au from the Sun. Such an event constitutes akind of dynamical horizon for all studies of the past Solar System bodies'dynamics.

HD 7977 and its possible influence on Solar System bodies