Consider the ellipse  $S_1=\frac{x^2}{9}+\frac{y^2}{8}-1=0$. Let  $S_2=0$  be a parabola on the right of y-axis confocal with $S_1=0$  having vertex at the centre of  $S_1=0$. Let P be the point of intersection of the parabola and directrix of the ellipse in the 1^st quadrant. If tangent at point Q in 1^st quadrant on  $S_1=0$ and the line joining point P with the focus of  $S_2=0$ intersect on the auxiliary circle of  $S_1=0$ then the value of  $9{\sin }^2\theta$  is __________
( $\theta$ is the eccentric angle of the point Q)