Jupiter has a 23 moons other than the large Galilean satellites. These are
much smaller than the Galilean moons. An example is
Amalthea, shown in the image to the right
(Ref), which orbits inside the orbit of
Io (its color may be due to particles from the volcanoes on Io).
Many of these
moons may be asteroids captured in the immense gravitational field of Jupiter.