Template:Minor planet color code legend/doc

Color code for orbital classification of numbered minor planets
The colorization is based on the following defining criteria of a minor planet's (MPs) orbital elements such as semimajor axis a, perihelion distance q, aphelion distance Q, and orbital eccentricity e. Figures below give the actual number distribution of MPs by color-coded orbital class. They are used in the color-coded partial lists of minor planets.


 * (a) NEO-subgroups with number of members: Aten (255), Amor (1,275), Apollo (1,566) and Atira (8) asteroids.
 * (b) Including 35 unclassified bodies: 6144 Kondojiro, 8373 Stephengould, 9767 Midsomer Norton,,, , , , , , , , , , , , , , , , , , , , , 514107 Ka`epaoka`awela, , , , , , , , , (colored as for being unclassified).

Sources for classification
The orbital classification largely follows JPL's conventions (see definitions below), except for the boundary of inner/outer main-belt asteroids which are grouped by the two major Kirkwood gaps (a at 2.5 and 2.82 AU, instead of JPL's 2.0 and 3.2 AU). Also the Apollo, Amor, Aten, and Atira groups have no distinct color and are displayed with one color as NEOs. For outer main-belt asteroids, the criteria "q > 1.666 AU" has also been added.
 * MCAs Asteroids that cross the orbit of Mars constrained by (1.3 AU < q < 1.666 AU; a < 3.2 AU).
 * JTs Asteroids trapped in Jupiter's L4/L5 Lagrangian points (4.6 AU < a < 5.5 AU; e < 0.3).
 * CEN Objects with orbits between Jupiter and Neptune (5.5 AU < a < 30.1 AU).
 * TNO Objects with orbits outside Neptune (a > 30.1 AU).
 * MBA (middle) Asteroids with orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU).
 * MBA (inner) Asteroids with orbital elements constrained by (a < 2.0 AU; q > 1.666 AU).
 * MBA (outer) Asteroids with orbital elements constrained by (3.2 AU < a < 4.6 AU).
 * APO Near-Earth asteroid orbits which cross the Earth's orbit similar to that of 1862 Apollo (a > 1.0 AU; q < 1.017 AU).
 * ATE Near-Earth asteroid orbits similar to that of 2062 Aten (a < 1.0 AU; Q > 0.983 AU).
 * AMO Near-Earth asteroid orbits similar to that of 1221 Amor (1.017 AU < q < 1.3 AU).
 * ATI	Asteroid orbits contained entirely within the orbit of the Earth (Q < 0.983 AU). Also known as Interior Earth Objects.

Remarks

 * Unclassified: A handful of minor planets can not be classified with the above given criteria. These are objects with a semi-major axis corresponding to those of Jupiter trojans, but with an eccentricity larger than 0.3. Others are Mars-crossing (MPC) outer main-belt asteroids (JPL).
 * Divergent classification: A relatively larger number of objects may be differently classified . In particular, JPL's Small-Body Database and the Minor Planet Center's website often do not agree on the distinction of main-belt Hungaria and Mars-crosser asteroids.
 * : adjust the background color of the heading sections in to the above color scheme with background. This allows for a basic distinction of NEOs, MBAs, Jupiter trojans, centaurs and TNOs at first glance. Since the background of the infobox itself already uses a light-grey background color, the heading sections should use   for all main-belt object articles, irrespective whether they are inner, middle or outer belt asteroids.