What does 9 equals p in the s s stand for?

9 P. in the S. S. equals 9 planets in the solar system

EDIT: Which is no longer the case, as Pluto has now been classified as a dwarf planet.
9 planets of the solar system
9 equals planets in the solar system
9 planets of the solar sytem this must be an old question as Pluto (the orbiting sattelite, not the dog owned by Mickey Mouse) has been downgaded from a planet so it should be 8 P of the SS