Two NASA missions in 2015 might see the number of official planets jump from eight to 10 — and yes, that could mean a comeback for Pluto.
NASA's New Horizons spacecraft is currently hurtling towards Pluto and its many moons for a unique flyby of the body which has been officially classed a ‘Dwarf Planet’ since 2006.
Meanwhile the Dawn spacecraft is coming ever closer to Ceres, also a dwarf planet, which is located in the asteroid belt between Mars and Jupiter.
Scientists will receive images of both dwarf planets from unique new vantage points in 2015, which will reveal the answers to mysteries including what colour Pluto actually is, and whether or not Ceres is the Death Star in disguise.
And -- maybe -- whether or not they're actually planets after all.
— NASA (@NASA) February 25, 2015
Over at Phys.org he writes that “I expect 2015 will be the year when general consensus, built upon our new knowledge of these two objects, will return Pluto and add Ceres to our family of solar system planets.”
Weintraub argues that both bodies are spheroid and orbit a star, and says the argument that they have not “cleared their neighbourhood” of asteroids or other large moons does not hold water. He says, for instance, that if Earth were in the Kuiper belt with Pluto it too might not clear the area of asteroids, and would not be considered a planet.
What is clear is that both missions will reveal lots about both Ceres and Pluto. On Ceres, astronomers want to know if the world has water, and an atmosphere. It might even have frozen lakes and a sub-surface ocean. For Pluto’s part they’ll be looking to find out what its atmosphere is made of, if it has an ocean below the surface and how its magnetic field works.
And it’s not inconceivable that the IAU might decide to reclassify them again — after all, in a recent debate it held on the issue two out of three scientists asked said that they believed Pluto, at least, was a planet.
New Horizons will arrive for its high-speed fly past Pluto on July 15 2015, while Dawn is already coming closer to Ceres and posting amazing pictures every week.