So, it seems there's a new twin paradox thread every day, but I don't think I've seen this particular situation looked at. The two twins move towards each other each in a circular orbit, and at one point they get close enough to each other that they can compare clocks directly (but their circles do not cross each other: they meet on a line tangent to both circles). Now, from the symmetry of the situation it appears to me that each twin will see the other as having the exact same age every time they meet at the intersection point. But if each twin looks at the other at a different point along their respective orbits, it seems to me that whether or not the twin will see the other as having a slow clock (or a fast one) will depend on their respective positions, and in particular whether or not they are approaching each other or moving away from each other along their orbital paths. My question is two fold: (a) What would a space time diagram of this look like, since the motion for the twins is two dimensional (would we need a three dimensional space time diagram, or some form of parameterization?). Furthermore, if one twin is considered at rest, the motion through space for the other twin seems like it is going to be weird enough without throwing in the added complication of time. I'm guessing each twin will see the other as following an elliptical path? (b) Since this is circular motion for both twins, and hence acceleration, would there be any need to bring general relativity into it, and if there is no need, would it be simpler or more complex to do so if it's possible?