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Did You Hear About Pluto?


Life + Learning

  • Pluto

Jessica, Queen's Square | February 1, 2018

Can you name all the planets in our solar system?  Let’s name them together: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, PLUTO!  Did you name Pluto? Or did your solar system end at Neptune?  

Since its discovery in 1930, Pluto was considered a planet.  That distant, mysterious ninth planet on the very edge of our solar system.  In 2006, all of that changed when astronomers kicked Pluto out of the solar system and relegated it to “dwarf” planet status.

If you missed the finer details of Pluto’s demotion, here’s what happened.  In 2005, American astronomer and professor Mike Brown led a team that discovered another world in our system beyond Pluto.  Based on early reports, this new world, which Brown and his colleagues called Eris, was either larger, or the same size as, Pluto.  Eris’ discovery launched a fervent debate over whether it should be classified as a planet and part of this discussion involved deciding on the exact definition of the term “planet.”

It’s this wrangling on a definition that sealed Pluto’s fate.  After much debate (some of it heated) the International Astronomical Union (IAU) decided that in order to qualify as a planet, celestial bodies must meet three criteria.  Sadly, this new definition knocked Pluto out of planet status.  Pluto (and Eris if you were curious) are now considered “dwarf planets” or Kuiper Belt (rhymes with piper) objects.

If you want a more detailed and thoroughly enjoyable account of the entire saga, you can read about it in Mike Brown’s own words in his book, How I Killed Pluto and Why it Had it Coming.

However, most people passionate about Pluto and disheartened by its demotion don’t blame Mike Brown.  They blame prominent astrophysicist, Director of the Hayden Planetarium, and snazzy dresser Neil deGrasse Tyson.  Tyson is the most well-known astrophysicist even among those that don’t follow astronomical news closely.  After Pluto’s status change, much ire, some in the form of angry letters from elementary school students, was directed at Tyson.  He took it all in good humour and even published a few of these letters in this book The Pluto Files.  The Pluto Files tells the history of Pluto starting from its discovery for all you Plutophiles out there!  Neil deGrasse Tyson has a unique gift for making science and astronomy accessible for everyone and his books are worth reading for anyone looking to learn more about our wonderful universe.  Be sure to check out his latest book Astrophysics for People in a Hurry.

Based on the heated debate over Pluto’s planet status, debate that continues to this day, I’m not the only one passionate about this distant world.  Although I have never gone so far as to write hate mail to Neil deGrasse Tyson!  Despite its official classification, decided by a handful of astronomers, Pluto will always be a planet to me.  My solar system has nine planets.  What about yours?

How I Killed Pluto and Why It Had It ComingThe Pluto FilesAstrophysics for People in a Hurry