Distribution of the angular momentum vectors of the most massive minor planets. The reference plane H_x–H_y is chosen to be the invariant plane of the Sun-planets system. For each object, the angular momentum vector H has been scaled by its module |H|, that is, displaying the unit vector , such that the several orders of magnitude difference in the lengths of arrows can be avoided. The red lines are the projections of on the H_x–H_y plane. Panel a: for the five dwarf planets, together with Jupiter. Panel b: for the 279 minor planets with measured masses from Sect. 2.1.1.