AbstractCometary impacts on Earth, as comets themselves, especially aperiodic ones, have been much less studied compared to asteroids. Nevertheless, despite the rarity of such impacts, they occurred in the past and cannot be ruled out in the near future. Moreover, the impacts of interstellar and, in principle, even intergalactic objects with hyperbolic orbits are possible. One such comet 2I/Borisov has been discovered quite recently. To assess the influence of such objects on Earth, we carried out numerical simulations of the impacts of cometary nuclei with diameters of 1 and 3 km on solid Earth at speeds of 70 and 170 km/s at an angle of 45° to the surface. Modeling was carried out using a hydrodynamic computer code with allowance for thermodynamic properties of a dusty core and shell of a comet and Earth’s crust in solid and molten state. Fluxes of thermal radiation on Earth’s surface were determined based on an approximate solution of the radiation transfer equation, taking into account optical properties of vapors and air. We estimated areas affected by air shock waves, masses of material ejected into the atmosphere and atmospheric pollution, magnitudes of earthquakes, areas of potential fires. The most dangerous direct effect is associated with the possibility of fires in areas that are much larger than both the size of an impact crater and the area of low-velocity ejecta from a crater, ranging in diameter from 3000 km with the minimum of considered impact energies up to 14 000 km with the maximum impact energy. Long-term effects of the impacts are associated with air pollution by fine dispersed ejecta, chemical components, darkening of the atmosphere.