14 DAY TRIAL // The decision of the International Astronomical Union (IAU) to declassify Pluto as a planet, and to move it to the lesser class of “dwarf planets” sparked widespread protests and disagreement in 2006. The move resulted from the fact that the new definition of the term “planet,” coined at the IAU meeting in Prague, the Czech Republic, added a number of conditions that Pluto did not meet. One of them refers to the object to be termed planet to have cleared its vicinity of any other objects. However, it may be that Pluto will be named a planet again soon, but not by scientific consensus, but by scientific data.
Earlier this year, the US state of Illinois decided that Pluto had been unjustly degraded from the planetary status, and took IAU's decision as a personal affront. Clyde Tombaugh, the scientist who discovered the planet in 1930, was born in the state, and authorities questioned the decision based on the fact that only four percent of the 10,000 representatives the Union had were present at the voting procedures, NewScientist reports. At this point, there are officially only eight planets in the solar system, and people who grew up with nine didn't take the decision too kindly.
The situation around Pluto is not very simple, so to speak. If the body is elevated to planetary status, then other objects in the outer asteroid belt (Kuiper's Belt) could be classified as planets too. On the other hand, it may be that objects as large as the Earth, or even bigger, may not be classified as such when they are discovered. Some scientists prefer a simpler definition of the word – as in everything that has sufficient gravitational force to be shaped like a sphere.
Others believe that the celestial bodies need to exhibit signs of past or present activity, and to have cleared the orbits around them of any debris. Critics to the latter line of thought reason that this definition, which prompted Pluto's declassification, would also make Earth a non-planet, seeing how it couldn't clear its orbit of any asteroids, if it were to be moved in the Kuiper Belt. “It is a horrible mistake. Any definition that allows a planet in one location but not another is unworkable. Take Earth. Move it to Pluto's orbit, and it will be instantly disqualified as a planet,” Southwest Research Institute (SwRI) expert Alan Stern, who is the leader of the NASA New Horizons mission to Pluto, says.
Experts keeping an eye on New Horizons and New Dawn – the mission to the dwarf planet Ceres and the large asteroid Vesta – believe that these investigations will reveal a large degree of complexity on these formations, which would merit them the name of planets, despite their size. In addition to these matters, the IAU also has to accurately delimit giant gas planets from brown dwarfs, as well as the exact meaning of an Earth-like planet orbiting another star. In the case of Pluto and Ceres, by 2015, we will have a clear answer, as then the space probes will reach their respective targets.