Answer: The International Astronomical Union (IAU) .
The International Astronomical Union (IAU), a worldwide organization of astronomers, reclassified Pluto as a dwarf planet. IAU defines a planet as a celestial body that has the following qualities .
you will see contour elevation numbers. This is the elevation of the contour line, relative to mean sea level. Contour lines that are relatively close together indicate a slope that is fairly steep.
