@freemo @olamundo A method that was surprising to me is detecting a second planet by noticing orbital period variations of the first one. I think that it should be in principle doable even if their orbits are perpendicular, though the effect then might be smaller (but still nonzero).

@robryk

Yea the wobble method, which is closely related to the doppler shift method in principle, works well too. One issue with both these methods, as I understand it, is they are more effective picking up more subtle effects (like planets far away) when there are fewer planets orbiting the star. Otherwise the pulls tend to average out and you get less wobble.

@olamundo

@freemo @olamundo Even more so, they are good at detecting sibling planets that have some simple (small numerator and denominator) ratio of orbital periods.