Pluto is now called a dwarf planet because of a reclassification that took place in 2006 by the International Astronomical Union (IAU). Prior to this reclassification, Pluto was considered the ninth planet in our solar system. However, with the discovery of other similar-sized objects beyond Pluto's orbit, such as Eris, the IAU redefined the requirements for a celestial body to be classified as a planet.
According to the IAU's new definition, a celestial body must meet three criteria to be considered a planet. Firstly, it must orbit around the Sun. Secondly, it must have sufficient mass for its gravity to shape it into a nearly round shape. Lastly, it must have cleared its orbit of other debris. It is this last criterion that led to Pluto's reclassification.
Pluto, along with other objects in its region of the solar system called the Kuiper Belt, has not cleared its orbit. It shares its orbital path with many other objects, making it unable to meet the final requirement. Thus, Pluto was redefined as a dwarf planet, which is a separate category for celestial bodies that meet the first two criteria but not the third.
So, while Pluto remains a fascinating and significant object in our solar system, it is now referred to as a dwarf planet due to the IAU's redefinition.
Why is Pluto now called a dwarf planet?
write in your own wrods
1 answer