An Emotional Journey to the planet Pluto

“Space and Universe” is a field that has always magnetized me (I would not say right from the birth, but surely after some months from the birth or may be some days!)। I don’t know why stars have always appeared to be more effulgent to me than to anyone else. Is it because of the fact that Rakesh Sharma, went to Space in 1984, the year of my birth? The reason may be anything but the fact is that the word Solar system (henceforth referred to as SS) has always seemed more romantic to me than a SRK-Kajol flick! Until 2006, the first thing that used to come to my mind for the word SS was the Sun and the nine planets. And of all the planets and their moon, Pluto has always been my favorite one.

fig.1: An artist's impression of Pluto from its largest moon, Charon

One reason of this may be that Pluto is always depicted by the color blue due to its extraordinary cool temperatures (of the order of -240 degrees) and blue is my favorite color. I have dreamt of roaming on it because it was probably the farthest discovered planet in the SS till that time. Though it may sound strange but just the very remote probability of surviving on it due to its hostile conditions has always attracted me towards it. I even dreamt of buying a few kms land on the 2500 Km long planet!

I developed interest in the planet as early as in my school. Here I can easily recall one line which was taught to me in school to remember the complete list of nine planets (including Pluto) in the order in which they orbit around the Sun:; "My very educated mother just showed us nine planets". In fact that’s how most of us might have learned them. But I had never thought, even in my wildest dreams, at that time that Pluto will, one day, cease to be a planet and the same line will be reduced to, say, "My very educated mother just showed us nothing". I used "nothing" because I feel that the list of planets is incomplete without Pluto which has been robbed off its planetary status by the controversial decision of the International Astronomical Union (IAU) in Aug, 2006. But why did they do so? Why is Pluto not a planet anymore? What sin has it done? Why is it demoted? Yes, this is one of the most heart-breaking questions, I have ever faced. Here lies the real story behind the scenes:-

Pluto was discovered by Clyde W. Tombaugh in 1930 when he was just 22. Since then, astronomers have been continuously turning up with larger and larger objects in the Kuiper belt (the belt in which Pluto lies, see fig.2 below).

fig.2: Depiction of Kuiper belt objects behind the orbit of Neptune

One such object was Eris which was discovered in 2005 by Mike Brown. Its mass was approximately 25% more than that of the Pluto. Similarly there were 3 more such objects that were discovered with the help of mighty Hubble Space Telescope. In the end in Aug, 2006, the members from IAU voted for the new definition of planets. According to them, for an object to be a planet, it needs to meet these three requirements:

• It needs to be in orbit around the Sun - Pluto qualifies this one!
• It needs to have enough gravity to pull itself into a spherical shape – still unsure for Pluto but may be yes, it qualifies!
• It needs to have "cleared the neighborhood*" of its orbit – (Lo kallo baat!) Here's the rule breaker. According to this, Pluto is not a planet.
  

The meaning of the phrase “cleared its neighborhood” is that as planets form, they become the dominant gravitational body in their orbit in the SS. As they interact with other, smaller objects, they either consume them, or blow them away with their gravity. Pluto is only 0.07 times the mass of the other objects in its orbit. The Earth, in comparison, has 1.7 million times the mass of the other objects in its orbit.

And hence Pluto is now considered as a dwarf planet. If you ask for my comment on this, I shall say that it is really hard to find anyone who thinks this is necessary and useful on the part of IAU. Instead, people across the globe wounded black bands around their telescopes to commemorate the heinous decision of IAU. And they still have those bands in place! In fact, Mar-13-2009 was "Pluto Day" in Illinois. Some people believe that this is an “insult” to the discovery of Clyde Tombaugh. Though the union tried to calm down the hysteria by declaring another class of objects called Plutoids in June, 2008 which would contain Pluto, Eris and Sedna but the people still have sore throat for taking it in.

Some IAU scientists say that it’s just a matter of time that Pluto was discovered before other planets. My question to these people is that if tomorrow they discover a galaxy which is many times bigger than our Milky Way galaxy, then will they also demote Milky Way galaxy’s status to a dwarf galaxy? Discoveries and inventions never stop. Nor do they tamper with existing legacy of the objects. They just better them.

However, there are people who have accepted IAU’s decision but with a pinch of salt. They say that even though Pluto is now just a dwarf planet, it is still a fascinating target to study. And that’s why NASA has sent its NEW HORIZONS space-craft, ironically in 2006 itself, to study the surface and demography of Pluto and it will reach there in 2015. Let it be.

In the end, I would also agree that it really doesn’t matter that what is the status of Pluto by IAU. It will always remain as fascinating to me as it was ever before.