In: Physics
Inspired by this question, are there any known planetary systems with largely varying planes of orbit? For example a system where two planets have perpendicular planes?
Many planets have been found where their orbital axes do not align with the rotation axis of their star. This is achieved using measurements of the Rossiter-McLaughlin effect in transiting systems or by observing planets transit over spotted features on a star's surface.
As the stellar rotation axis is highly likely to coincide with its protoplanetary disk axis, the planets must (now) be orbiting out of this plane and some are retrograde. About 1/3 of hot Jupiter's are misaligned in this fashion.
It seems likely that many of the misaligned hot Jupiters could have planetary siblings orbiting further out that are more nearly in the rotation plane of the star. On the other hand, whatever event caused the misalignment could have wrecked the planetary system.
There is at present I think only one solid example where the measurements suggest non-coplanarity and that is in the planetary system surrounding Upsilon And A. Using radial velocities and astrometry from the fine guidance sensors on HST, MacArthur et al. (2010) were able to establish that the c and d planets (i.e. the 2nd and 3rd planets in the system) were inclined at angles of 30