Absolute differences in position, velocity, and direction, in “sliced” planes at different positions from the Sun along the X-axis of the ISD-frame. The difference between the case for β = 1, Q/m = 0, and β = 0.5, Q/m = 0 is shown. The red regions denote trajectory differences of more than 1 AU (left), velocity differences of more than 5 km s^-1 (middle), and angular differences of more than 5 degrees (right). The plot illustrates in what extent the straight-line approximation can be used.