The theory of gravitational anti-screening, which has previously been applied to various astronomical observations as an alternative to dark matter, is now applied to the solar system. The effect that gravitational anti-screening has on the precession rate of the planets will be determined and compared to current observations. In addition, the effect that gravitational anti-screening will have on certain orbital parameters of long-period comets will be determined. The set of 119 long-period

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... ts that are considered in this paper have a broad peak of aphelion distances, based on current gravitational theory, centred at approximately 50 kAU. In the case of gravitational anti-screening, these aphelion distances will be shown to be greatly reduced to a narrow distribution centred at approximately 10 kAU. It is further found from the theory that comets orbiting at this distance will have orbital speeds approximately 20% greater than that predicted from Newtonian gravitational theory.