International Astronomical Union upgraded Pluto to a dwarf planet three years ago . It also designated March 13 , 2009 , as `` Pluto Day '' in honor of the date that its discovery was announced in 1930 . 90 percent of the critical letters the IAU received afterward came from North America . In spring , California lawmakers restored ` ` full planetary status '' to Pluto . Some people say the IAU 's definition of a planet does n't make sense .
International Astronomical Union upgraded Pluto to a dwarf planet three years ago . 90 percent of the critical letters the IAU received afterward came from North America . In spring , California lawmakers restored ` ` full planetary status '' to Pluto . Some people say the IAU 's definition of a planet does n't make sense .