Orbital trajectories of Proxima c corresponding to the best-fit prograde (left panel) and retrograde (right panel) solutions (whose parameters are listed in Table 2). A thicker line indicates that the planet is closer to the Earth. The orange arrow shows the velocity vector of Proxima c at the effective GDR2 epoch, and the red arrow the corresponding reflex velocity of Proxima from its PMa (scaled by 10 000×).