April fools! I know I am a day late with this, but I was surprised to find that this was a common thread appearing on my Facebook feed over the weekend. As is common when “news” appears on social media, an “article” was being passed around that seemingly few people even bothered to read. Instead, the headline that Pluto was a planet once again was enough information as they shared it with all of their friends and family. If one bothered to read it, they would quickly (I hope) notice the clear satire in the article. Surprisingly, Pluto was not renamed due to its similarity to the famous Disney character. And no, there is no new category of “hyper-planets”.
Although this article definitely caught my eye, I realized that many people most likely have no idea why Pluto was dropped as a planet in the first place. It all happened during a meeting of the International Astronomical Union (IAU) in August 2006. During this assembly, the world’s most renowned astronomers voted to establish a new set of criteria for being a planet. The list provided below is being quoted directly from this source.
- It is in orbit around the Sun.
- It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape).
- It has “cleared the neighborhood” around its orbit.
Unfortunately, Pluto fails to meet this third requirement. For objects that meet the first two requirements, but fail the third, the new designation “dwarf planet” was created. Therefore, unless a new discovery or another vote by the IAU, Pluto will remain as it is.