How Many Planets are there in the Solar System?

Planets on their orbits. Source: Google

Its really disturbing how I can become so outdated in this so called twenty-first century world when technology plays major role in each and every part of our life. Despite all the resources present right in my proximity, I still continue to remain outdated, which is evident as I keep hearing and coming across something new almost everyday. I mean 'new' or rather news to me, but not to others. But I think I can forgive myself for not knowing the silly stuffs, and of course not everybody can know and keep updated with everything. 

I can't however forgive me for failing to know the number of planets in our Solar System. Till couple of weeks ago, I was so confident enough of my ideas on solar systems (at least pertaining to the number of planets, and their names). As a matter of fact, I have been fondly known to my friends as a 'very updated' person because I spend fair amount of time reading news papers, watching news and discovery channels, etc. Now I feel shy even to think of that. If it wasn't for the Philosophy of Science which I am currently taking and struggling to understand, humiliating enough, I wouldn't have known that answer; the answer which even the elementary students might have right on their lips. 

I am not a fan of Philosophy nor very enthusiastic about the subject, but when I am left with no other options than to take it, all I have to do is to go the class, be on the very back seat, and daydream for hour and fifteen minutes. But now I can't help thanking this course for updating me with the basic general knowledge! I have often boasted of my excellent performance in high school Geography, and Physics subjects. So I had no doubt that there are a total of nine (9) planets in the Solar System. I recited the their names: "Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto" which came out exactly nine.  But it wasn't until last week that I learn that there are only eight planets orbiting around the Sun! How come? This is because Pluto has been downgraded to a mere Dwarf planet. 

Pluto, a Dwarf Planet. Source: Google

You might be wondering why did I come across such thing in the philosophy class, which I intend to address in a few paragraphs that follow. The very decision of downgrading Pluto to Dwarf planet has sparked off so many philosophical questions, and in fact it has become a very controversial issue among the scientists and philosophers. The problems lie on the complexity of the very definition of Planet, method employed for making decisions (which are based on majority voting), interpretation issues, so and so forth. While some scientists opposed the decision to deprive Pluto the Planet-hood, majority of scientists who were present at annual IAU (International Astronomical Union) conducted in Czech Republic on 24th August, 2006, voted in favor of it, subsequently which Pluto was officially taken out of the solar system. 

How and why was Pluto deprived of the Planet-hood? The issue popped up short after a major discovery by an astronomer named Mike Brown of California Tech, who discovered an Object slightly bigger than Pluto. He claimed it to be the tenth planet, and quite naturally everybody were excited that our solar system is indeed going to get the new planet. However, the very discovery questioned the status of the planets, and finally the IAU had to redefine what Planet is. Turns out, the new definition saw more stringent criteria than earlier definition. Out of three main criteria set out by the IAU committee, Pluto passed the two which I am not interested to discuss here. The third criterion which requires a planet "to have “cleared the neighborhood” of its orbit" (Universe Today) is the one which Pluto doesn't fulfill, thus depriving it the Planet-hood. 

It is being argued that since Pluto is not "massive" enough, it can't create its own gravity, which in turn can't clear its neighborhood. Now not only did Mike Brown's Planet X failed to gain the Planet-hood, but in due course of time it brought down Pluto to a mere Dwarf planet. 

Whether one support it or not, the decision has been made, and plate-form has been set for philosophers and scientists to debate on. 

Note: Its not proof-read, so bear with the grammatical errors. 

Reference: 

http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/