The variation in gravity due to height is given by g'=g(1-2h/R). Here, if the value of height is kept just equal to the radius value, then the result is -ve. This implies that when a body is projected from the earth, after it crosses the boundary of gravitational pull of the earth, then there must be another heavenly body just after that boundary to pull the object towards it since only the direction is changed not the magnitude, isn't it?