Pluto is a planet again!

Back on 24 Aug 2006, the International Astronomical Union, unceremoniously dethroned Pluto from the league of planets. The cold clump of ice and rock swaying in the darkest recesses of our Solar System for the past 4.6 bn years (much longer than the people who want to decide its fate as a planet) may not have taken this to heart but it sure made a few of us, who loved chanting the nine planets of the solar system back in our schools, a bit uneasy.(Read more on Pluto’s Dethronement: 1. 2.

Now, 8 years later, the IAU has decided that they committed a mistake back then, and that Pluto is actually a planet! Lucky for Pluto, it had to wait only 8 years (infinitesimally small considering how long it has already lived!) for the justice to come. (Read on: 1. The Comic Version 2. Intellectual Version 3. Some Wiki


6 thoughts on “Pluto is a planet again!

    1. That’s correct Atul. Thanks for your comment. What I don’t seem to quite understand is why the debates again now. Did they do a bad job previously before changing the status of a planet? Or was it a genuine mistake?


  1. Hello,

    Before 2006, there was no official definition of Planet, so Pluto was accepted as the 9th Planet. But it was found over decades that Pluto is just one of many rocky, icy objects in Kuiper belt. Eris, a similar object which is 27% more massive than Pluto was discovered in 2005. With the new definition of Planet by IAU, Pluto didn’t make it and was classified as Dwarf Planet (that too the 2nd largest after Eris).
    There are large number of defenders for Pluto as a planet, which have kept this debate ongoing, trying to come up with loopholes and discussions.
    On July 14, 2015, New Horizon’s probe will make a Pluto flyby, the first such mission to make detailed observations and measurements about it.
    So I reckon, until then, officially Pluto will remain a dwarf planet.

    Definition of a Planet:
    A Planet is a celestial body which:
    1. is in orbit around the Sun,
    2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
    3. has “cleared the neighbourhood” around its orbit.



    1. Thanks Atul. So basically, the problem seems to be the definition. This can be altered to adjust exceptions. Once that’s done, Pluto can be brought back to the status of a planet again.


      1. That’s the thing. One must not put their belief’s and personal opinion before Science just to alter the solution according to their needs.

        The good thing about Science is, its true whether or not people choose to believe in it.


      2. That’s absolutely correct Atul. The only thing that distinguishes science from everything else is repeatability. Just like with this definition, they reverse engineered it by observing the major planets. Just like the primitive definition of metals, which did not hold when Mercury (the metal) was discovered. We cannot make a formal definition for something we did not create. We just have to observe and note. Unfortunately, we can only observe so much.


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