There are 12 planets in our solar system

I take an inordinate delight in the overturning of orthodoxies of science. So I'm hoping that this proposal will get through. Basically the back story is that Pluto's status as a planet is either anomolous or it creates anomolies; its size and orbit mean that either there are objects that are better qualified to be planets or that it should not be classified as one. So a tidying up exercise has been attempted by the International Astronomy Union (IAU) which has been naming celestial bodies since 1919. The whole affair has meant that the issue of what constitutes a planet must be addressed.

The IAU ... agreed to come up with a scientific definition for planets. ... two conditions must be met: it must orbit a star without being a star itself, and it has to be big enough for its gravity to pull it into a spherical shape.

And this, in turn, means that they can then face the issue of what our solar system is made up of planetwise, and it means that

"Although Pluto remains a planet by the proposed definition, it will generally be preferable to call it a pluton to emphasise its role as the prototype for a physically distinct category of planetary bodies. Plutons are defined as having orbits around the sun that take more than 200 years to complete and are tilted with respect to those of the classical planets. These differing characteristics suggest that plutons have a different origin to the classical planets.

It also 'adds' three planets to the solar system [strictly, upgrades the status of three objects]. So celebrate the coming of age of Charon, Ceres and Xena. It may be that there could be more,

The IAU is already monitoring 12 more candidate planets, any of which could be upgraded in future. These include Varuna, Quaor and Sedna, all Pluto-like objects that reside in a region on the fringe of the solar system known as the Kuiper Belt.

Perhaps we might prefer to think of the solar system as having 8 planets and between 4 and 16 plutons ...
Taxonomy is an interesting subject, eh? After all, our naming and categorising makes little difference to the existence of these objects. Its purely for our own purposes.
Adam gave names to all the animals, and still it continues, only now we're on to celestial objects.
Guardian Unlimited | Science | Pluto survives as solar system acquires three more planets: Filed in: planets, solar_system, definition