Pluto may be able to reclaim its planet status once more. But, we’ve heard that before – in 2014, and again in 2015. So, why would this year be any different for the dwarf planet? Data gathered during the New Horizons mission, which concluded last summer, has inspired some scientists to revisit the issue after they spotted clouds around the planet/non-planet/planet. It’s possible that this new evidence will heat up the debate once more, forcing scientists from around the world to vote on whether Pluto can be called a planet again 10 years after being stripped of that title.
To get a grip on the current situation, it helps to understand how Pluto lost its “planet” title in the first place. The International Astronomical Union (IAU) is the global group of experts who agree on what it means to be identified as a planet in our solar system. There are three requirements: orbit around the sun, have sufficient mass to assume hydrostatic equilibrium (aka “must be orb shaped”), and must have ‘cleared the neighborhood’ around its orbit (a fancy way of saying it’s the biggest thing in its orbit).
In 2006, members of the IAU voted to strip Pluto of its planet status because it couldn’t earn that third checkmark. Neighboring Eric is 27 percent larger than Pluto, which knocked Pluto out of the running. Some argue, though, that Pluto was judged unfairly, since some 9,500 members of the 10,000-member international union weren’t present to vote, and of the members who were in attendance, a significant portion backed a resolution to redefine Pluto as a “dwarf planet.”
As NASA unpacks the massive amount of data retrieved during the New Horizons mission, new information is coming to light about the nature of the rock called Pluto. Most recently, Independent has reported that scientists spotted what appear to be clouds in some of the images of Pluto, which is the sort of evidence that some would use to argue for Pluto’s planetary status to be reinstated. Even though an atmosphere capable of producing clouds isn’t part of the IAU’s definition of a planet, many in the scientific community have argued that those rules are too stringent, including Alan Stern, the head of the New Horizons mission to Pluto. It shouldn’t be so difficult to determine what a planet is,” Stern told Space.com in a 2011 interview. “ When you’re watching a science fiction show like ‘Star Trek’ and they show up at some object in space and turn on the viewfinder, the audience and the people in the show know immediately whether it’s a planet, or a star, or a comet or an asteroid.”