The X-ray holes at the centre of the Perseus Cluster of galaxies are not all at the same position angle with respect to the centre of the cluster .
This configuration would result if the jet inflating the bubbles is precessing , or moving around , and the bubbles detach at different times .
The orientations which best fit the observed travel directions are an inclination of the precession axis to the line of sight of 120 ^ { \circ } and an opening angle of 50 ^ { \circ } .
From the timescales for the bubbles seen in the cluster , the precession timescale , \tau _ { prec } , is around 3.3 \times 10 ^ { 7 } \thinspace yr .
The bubbles rising up through different parts of the cluster may have interacted with the central cool gas , forming the whorl of cool gas observed in the temperature structure of the cluster .
The dynamics of bubbles rising in fluids is discussed .
The conditions present in the cluster are such that oscillatory motion , observed for bubbles rising in fluids on Earth , should take place .
However the timescale for this motion is longer than that taken for the bubbles to evolve into spherical cap bubbles , which do not undergo a path instability , so such motion is not expected to occur .