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Dwarf planets are celestial bodies that orbit the sun and have enough mass for their gravity to give them a nearly round shape, but unlike planets, they haven't cleared their neighboring region of other objects. Put simply, they resemble the more commonly known planets but are different in some fundamental ways.

This category includes Pluto, which was famously demoted from its planetary status in 2006. The reclassification of Pluto to a dwarf planet was mainly because it didn't meet the criteria of clearing its orbit around the Sun. There are other dwarf planets in our solar system, including Eris, Haumea, Makemake, and Ceres. Understanding the characteristics of dwarf planets helps to clarify why these celestial objects don't fit the full criteria for being considered one of the main planets of the Solar System.

The International Astronomical Union (IAU) is an organization that acts as the authority for naming and defining celestial bodies and their features. Founded in 1919, the IAU brings together professional astronomers from all over the world, promoting and safeguarding the science of astronomy through international cooperation.

One of the IAU's most notable decisions was the redefinition of what constitutes a planet. In 2006, their decision to reclassify Pluto as a dwarf planet was based on three criteria they established for defining a full-fledged planet: (1) it must orbit the Sun, (2) it must have sufficient mass to assume a nearly round shape, and (3) it must have cleared the neighborhood around its orbit. The IAU's definitions and classifications play a crucial role in the common understanding and communication in the field of astronomy.

Our solar system consists of the Sun and all the objects that are bound by its gravity. This includes eight planets, their moons, dwarf planets, and countless other smaller objects like asteroids and comets. Learning about the solar system is fundamental in understanding our place in the universe.

The decision by the IAU to reclassify Pluto impacted how we view the solar system's structure. Initially comprising nine planets, the solar system now officially consists of eight planets with Pluto being considered one of several dwarf planets, although it was the first to be discovered in 1930. The solar system's formation and dynamics, including the orbital characteristics of bodies like dwarf planets, are essential concepts for those studying astronomy and the space sciences.