Among other things, 2015 is the year of the protoplanets. Though Ceres dominates the news cycle currently, it will soon be Pluto’s turn. For almost ten years, the New Horizons spacecraft has been hurtling through the solar system and is now 2.9 billion miles from earth. In December 2014, it transitioned from hibernation to an active state, to the sound of a specially recorded version of “Where My Heart Will Take Me” by the English tenor, Russell Watson.
Principal New Horizons investigator, Alan Stern, says: “This is a watershed event that signals the end of New Horizons crossing of a vast ocean of space to the very frontier of our solar system, and the beginning of the mission’s primary objective: the exploration of Pluto and its many moons in 2015.” The spacecraft has already started sending back images of Pluto’s moons, Nix and Hydra, and a time-lapse film of Pluto and its largest moon, Charon.
In July, New Horizons will make its closest approach to Pluto. Even though New Horizons will pass very close to Pluto, about 7,750 miles away, it will not go into orbit, but continue to the Kuiper Belt beyond.
The purpose of the mission is to study the mysterious, icy world at the edge of the solar system. According to Alan Stern, New Horizons will “…make the first reconnaissance of Pluto and its satellite system to map the surfaces of those worlds, to map their surface composition and temperatures, to assay the atmospheric structure and composition, and give us, for the first time, an understanding of this third class of planet, not a terrestrial world like Venus, Mercury, Earth and Mars, not a gas giant like Jupiter, Saturn, Uranus and Neptune, but the most populous class of planet in our solar system, the ice dwarfs.”
As the mission proceeds, it is sure to reignite the debate over Pluto’s claim to planethood. In 2006, the International Astronomical Union (IAU) changed its definition of a planet, and demoted Pluto to the status of a “dwarf” planet. While the initial angry reaction has died down, Pluto has many supporters who believe that New Horizons will reveal that it has the complexity to be classified as a planet.
