These figures show Jupiter and Neptune with their leading (L4) and trailing (L5) Trojan clouds. These Trojan clouds are made up of small bodies with diameters less than 300 km. The gravitational attraction from the Sun and Planet are balanced near these areas (called Lagrangian points) and allows the objects to have orbits which are stable over the age of the Solar System. Jupiter's and Neptune's orbits are shown for reference as a solid line.
The Jupiter Trojan clouds have about as many objects in total as the main asteroid belt which is located between the orbits of Mars and Jupiter. The dashed circle around Jupiter shows its Hill sphere, or the area where Jupiter's gravity dominates that of the Sun. This Hill sphere is the region in which all of Jupiter's moons are found.
Neptune's Trojan clouds are probably more populated than the Jupiter Trojan clouds but because of Neptune's extreme distance from the Sun, the Neptune Trojans are harder to detect. Find out about the recent new Neptune Trojan discoveries .