Index covers the 26,446 bodies that have been given a name.

Bodies are stored sorted by semi-major axis, so a shell is a contiguous run of vertices and the brush costs one draw-range change rather than a per-body test.

Stretches the ecliptic-normal axis only. Nothing is displaced: at ×1 every body sits at its true position. Median inclination in this catalogue is 7.8761°.

This moves bodies away from where they are. The resonance gaps are gaps in semi-major axis, but a body’s distance from the Sun swings between perihelion and aphelion, so at a median eccentricity of 0.1473 a true-position plot smears every lane. Pulling this to 100% sets each eccentricity to zero while keeping a, i and the orientation, which parks every body at its own semi-major axis and makes the gaps sharp. The readout says which you are looking at.

Brightness is a density map: a pixel is bright because many bodies land on it. Per-point opacity is therefore scaled by the number of bodies loaded, so that switching tiers changes the resolution of the picture and not its exposure.

Off by default: when point size varies, brightness stops being a pure density map and the gaps get confounded with the size of the bodies around them.