Figure 15-13: Asteroids Outside the Belt (a) The combined gravitational forces of Jupiter and the Sun tend to trap asteroids near the two stable Lagrange points along Jupiter’s orbit. Note that the Sun, Jupiter, and either one of these points lie at the vertices of an equilateral triangle. (b) This plot shows the actual positions of all known asteroids at Jupiter’s orbit or closer. Green dots denote belt asteroids, deep blue squares denote Trojan asteroids, and red circles denote asteroids that come within 1.3 AU of the Sun. Most of the red dots are called near-Earth objects (NEOs). Comets are filled and unfilled light blue squares.

(b: Gareth Williams/Minor Planet Center)