We know that the orbit of a planet and its star is a conic section. For a closed orbit, it will be an ellipse described by x^2/a+y^2/b =1, or its equivalent equation in r and θ What would be the equation of the path under GR? and how will it approximate to a conic section when r(s)/r tends to be very small? (r is the tadial coordinate and r(s) its Schwarzschild radius). When r(s)/r is exactly 0, the path should be a straight line. Can someone please enlighten me?