Image via NASA

In 2006, the International Astronomical Union (IAU) decided to change the official requirements that constitute a planet, and as we all know, Pluto didn’t make the cut. Since then, the mere mention of Pluto generates controversy from all ends, with laypeople and scientists alike challenging the assertion that Pluto isn't a planet (newsflash: a dwarf planet is still a planet; just a smaller one). And now, Alan Stern, the principal investigator of NASA's New Horizons mission to Pluto, has challenged astrophysicist Neil deGrasse Tyson to debate what the definition of a planet should be and whether or not this definition should extend to Pluto and the other dwarf planets.

Some History:

In the early 2000s - following the discovery of objects similar to Pluto in the Kuiper belt, along with the discovery of Pluto’s moon, Charon (which is about half of Pluto’s size) - a growing number of scientists were arguing in favor of Pluto’s declassification. In 2005, the discovery of Eris, a Kuiper belt object 27% more massive than Pluto, led the IAU to set an official definition of what a planet is. During this conversation, it was decided that Pluto would be reclassified a dwarf-planet, a title it now shares with four other bodies in our solar system (Eris, Haumea, Makemake and Ceres).

Through the tightening of the proverbial belt on planethood, the IAU had the potential to dramatically reshape our solar system by opening the floodgates to dozens of new ‘planets.' Of course, this discussion did not take place without some strong emotions. Neil deGrasse Tyson believes that Americans, in particular, have a special non-scientific attachment to Pluto.

Perhaps this is because Mickey's dog, Pluto (the dog from the Disney cartoons), was named after the then-planet, or maybe, some of the attachment lies in the fact that an American discovered it. Whatever the case may be, scientists themselves were attached; at least those who took part in the New Horizons mission were. Earlier in 2006, they oversaw the launch of the billion-dollar spacecraft that is set to visit the last planet – the only planet Voyager didn't see.

Artist’s impression of how the surface of Pluto might look. The Sun is 1000 times fainter. Image via ESO/L. Calcada

However, emotions also run high on the other side of the spectrum. For the first time in human history, we have the technology to observe and classify thousands of objects in our solar system, which in turn, means we may be on the cusp of adding dozens of new planets to the roster. The name "planet" is near and dear to our hearts, since Earth is a planet and the planet club has always been very small. All of the sudden, the term ‘planet’ starts to feel a little crowded when you need more than ten fingers to count them all.

 The Challenge: 

And Sten wants to hash our the argument, once and for all. "I am challenging him to the equivalent of the 'Thrilla in Manila,'" Stern told NBCNews. "Before New Horizons gets to Pluto, I want him to accept the debate." That gives Tyson — the host of "Cosmos: A Spacetime Odyssey," a TV series that aired this spring on Fox and the National Geographic Channel — about a year to work the proposed debate into his schedule, if he so chooses. New Horizons is scheduled to fly by the Pluto system in July 2015,


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