2006年8月24日,全球的目光都聚焦在捷克的首都布拉格,在这里举行的国际天文学联合会大会上通过了新的行星定义,不再将传统的九大行星之一的冥王星视为行星,而将其列入“矮行星”.许多人感到不解,为什么从儿时起就一直熟知的太阳系“九大行星”概念如今要被重新定义?冥王星因何被“降级”? On August 24, 2006, the global attention was focused on Prague, the capital of Czech Republic. At the International Astronomical Congress held here, a new definition of the planet was adopted, no longer treating Pluto, one of the nine traditional planets, as a planet. , and to include it in the dwarf planet. Many people are puzzled why the concept of the “nine planets” of the solar system, which has been known since childhood, is now to be redefined. How has Pluto been demoted? "?