Since 2006, Pluto has been considered a dwarf planet.
the only planet that scientists do not consider a planet is Pluto, (but they also found new planets in the asteroid belt.)Pluto
Pluto, but some consider that Pluto is not a planet anymore.
August 24, 2006 is the date when Pluto was consider no more a planet.
no
A VERY small planet.
2006
Mercury, Mars and Pluto if you consider Pluto as a planet.
Ceres, Pluto, Haumea, Makemake and Eris.
Charon. It's more of a satellite than a planet, unless you want to consider Pluto/Charon as a double planet. That's a little awkward, since Pluto has been downgraded to a planetoid.
Because it is not big enough. It is classed as a dwarf planet.
Pluto. It is now considered a "Dwarf Planet", due to its tiny size and the fact that there are other bodies like Pluto in the outer Solar System.
Pluto didn't change; our ideas of Pluto did. It turns out that Pluto is smaller than originally believed, so eventually he was "demoted" to the status (newly-created) of a "dwarf planet". It is unlikely that he will oficially be declared (by the IAU) a planet again.