The International Astronomical Union votes on a new definition of a planet on August 24 of this year. If this definition is accepted, the list of planets grows from nine to at least twelve.

Mercury
Venus
Earth
Mars
Ceres
Jupiter
Saturn
Uranus
Neptune
Pluto
Charon
2003 UB313 a.k.a. Xena

If accepted, though, other bodies would qualify. How about planet Sedna?

In case you think that astrologers will have to change, many of them already believe that there are twelve planets.