Is Pluto a planet?

It's a simple question, but one scientists and space buffs have been debating for years.

Back in 2006, after long being known as a planet, Pluto was demoted to dwarf planet status. Nine years later, with the New Horizons spacecraft having given us the first close-up look at the distant body, the planet-vs.-dwarf-planet debate is once again front and center. Just listen to the experts who joined HuffPost Live on Tuesday.

"I don't think this flyby is going to change the result, that Pluto is demonstrably not a planet," said planetary scientist Carolyn Porco. "It never should have been a planet to begin with. This has been like a 70-year cold case of mistaken identity."

According to the International Astronomical Union , a planet is defined as a body that orbits the Sun, is big enough for gravity to have squished into a round ball, and which has swept away other objects in its orbital neighborhood.

Some still believe Pluto qualifies, including Jim Bell, president of The Planetary Society .

"In my personal opinion, this encounter so far makes Pluto demonstrably a planet like many others in the solar system," Bell told HuffPost Live. "Round, core, mantle, crust, atmosphere, five moons, active geology on the surface in the past, maybe in the present -- we'll find out."

Watch the debate over Pluto's planetary status rage on in the video above, and click here for the full conversation on HuffPost Live about New Horizon's flyby of Pluto.

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