  We consider the planar three body problem of planetary type and we study the
generation and continuation of periodic orbits and mainly of asymmetric
periodic orbits. Asymmetric orbits exist in the restricted circular three body
problem only in particular resonances called "asymmetric resonances". However,
numerical studies showed that in the general three body problem asymmetric
orbits may exist not only for asymmetric resonances, but for other kinds, too.
In this work, we show the existence of asymmetric periodic orbits in the
elliptic restricted problem. These orbits are continued and clarify the origin
of many asymmetric periodic orbits in the general problem. Also, we illustrate
how the families of periodic orbits of the restricted circular problem and
those of the elliptic one join smoothly and form families in the general
problem, verifying in this way the scenario described firstly by Bozis and
Hadjidemetriou (1976).
