Astrometric observations with the Hubble Space Telescope measured an inclination of 53° of the outer planet d, though this result relies on the precise orbital parameters which have been substantially revised since this was published. The observed transits of e suggest an orbit normal inclined within 9° to the line-of-sight, and a possible detection of the transit of an extended atmosphere around 55 Cancri b would, if confirmed, imply that it too is in an orbit that is close to edge-on. Between them, no measurement of c's nor f's inclination has been made. It had been thought that with five planets, the system cannot deviate far from coplanar in order to maintain stability. An attempt to measure the spin-orbit misalignment of the innermost planet reported that it was in a nearly polar orbit, but this interpretation of the data has since been challenged by a subsequent study, with noted inconsistencies between the implied and measured stellar rotation.