Pluto
The question over Pluto's planethood will likely be reignited by New Horizons mission. NASA, ESA, and M. Buie/Southwest Research Institute

In the same year the New Horizons mission was launched, Pluto was demoted to a dwarf planet by the International Astronomical Union, which said it did not meet three criteria needed to be classified as a "planet".

Since then, there has been widespread debate about its declassification, with a recent poll by the Harvard-Smithsonian Centre showing that, overwhelmingly, people want Pluto to be redefined as a planet.

The New Horizons spacecraft, due to wake up on 6 December, will likely reignite this issue. The spacecraft will begin its flyby of Pluto in January, reaching its closest point to the planet in July.

During the mission, it will collect huge amounts of data about Pluto and vastly expand our understanding of it.

At the time of Pluto's demotion, there was considerable resistance among the scientific community to the change, with strong opinions held on both sides.

Alan Stern, New Horizons principal investigator, has always maintained that Pluto is a planet. Speaking to IBTimes UK ahead of the wake up, he said that ironically, the debate has worked in their favour by keeping Pluto in the forefront of people's minds.

new horizons
The New Horizons mission launched in 2006 and has since travelled 2.9bn miles from Earth. NASA/KSC

"Frankly the discussion about what it is to be a planet helps bring people to the table. It's a human controversy and it's something people can understand – there's not a lot of maths or chemistry, everyone can have their opinion. So in terms of public engagement and interesting people in science, it's actually done us a favour because people will want to come along.

"If we were going to some other planet in the Kuiper belt like Eris or Makemake or Sedna, no one knows the name. But Pluto – that's almost a brand."

However, Stern also notes that the question of Pluto being a planet should never have arisen in the first place, as astronomers are not well placed to make that decision: "You wouldn't let a podiatrist perform brain surgery," he said.

"When you go to planetary science meetings you find the experts calling these objects planets because what else would you call them? They've got atmospheres, moons and rocky surfaces. They have all the attributes of planets. And I don't find it controversial at all in my community.

"It's just wild that the press took this hook line and sinker 10 years ago, when the astronomers made their vote. They just aren't the right crowd for this. My friend who's a planetary scientists at MIT, it well: he said the thing the public may discover most is that Pluto was a planet all along."

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