Fig. 4: Best-fit ejection conditions for Hokusai’s ejecta according to its visible impact rays.

a Best-fit ejection conditions as compared to the global ray system (white lines). Except for the curved ray in question, most rays are consistent with being formed by ejecta with uniform ejection angles of θ = 35–55° (Supplementary Fig. 4). The reported case is based on θ = 45°, excavation from the crater center of Hokusai, and the current rotational period of Mercury. Cases with the other excavation positions are reported in the Supplementary Figs. 3–4. Modeled ejecta particles are color-coded according to their ejection velocities. Bold white lines highlight several other non-radial rays that also indicate abnormal ejection conditions (Supplementary Fig. 5). b Enlarged view for the best-fit ejection conditions of ejecta that formed the curved ray. The color bar in panel a is also appliable here. c Flight times of Hokusai’s ejecta (in Earth hours) that can land around the orientational inflection branch of this curved ray. The assumed ejection conditions are annotated besides each group of ejecta that has the same azimuth of the excavation (ϕ). Image IDs used for this figure are listed in Supplementary Table 1.