Ever since the discovery of Pluto by Clyde Tombaugh in 1930 our Solar System was known to have nine planets orbiting the Sun. “My Very Eager Mother Just Served Us Nine Pizzas” was a popular mnemonic in my elementary school days to help remember the order of major planets from Mercury outward. But in 2006, a controversial decision by the International Astronomical Union—spurred in part by Caltech astronomer Mike Brown—changed the specifications on what officially classifies a planet in the Solar System, thereby stripping Pluto of its 76-year-old designation. The reclassification, done by an in-person vote at a meeting in Prague (at which only about 400 of over 9,000 IAU members were in attendance) has been a topic of debate—often fierce—in the astronomical community ever since, and now some scientists are demanding to have it redefined again.
This July the New Horizons spacecraft will perform its long-awaited flyby through the Pluto system, capturing unprecedented data and images of the distant icy planet and its companion satellites Charon, Nix, Hydra, Kerberos, and Styx. The first two worlds, in particular, will have their surfaces seen in high-resolution, allowing scientists to observe and map their features for the very first time. But as landforms come into view – craters, mountains, scarps, plains, and who knows what else – what will they be named?
This is where YOU come in.
After more than nine years of traveling through space the New Horizons spacecraft is now in the home stretch of its journey, with less than 120 days and 143 million kilometers to go before it makes its historic flyby of the Pluto system on July 14. It will be the first time we get a good close-up look at the distant world which had for over seven decades held reign over the frozen edges of our Solar System as the outermost planet, much like its namesake governed the cold darkness of the mythological Greek underworld.
Discovered on February 18, 1930, the ninth planet Pluto lost its “full” planetary status in August 2006 as the result of a highly-contested decision by the International Astronomical Union (IAU) to create a new class of “dwarf planets,” of which Pluto, Ceres, and the then-recently-discovered Eris became charter members. Seven months after New Horizons launched, the edict did not sit well with both many members of the planetary science community and the public, who were suddenly informed that little Pluto just didn’t measure up and had to be let go… nothing serious, right?
Wrong. It was a serious scientific issue for many people, and especially for Dr. Alan Stern, Associate Vice President of Space Science and Engineering at the Southwest Research Institute in Boulder, CO and principal investigator of New Horizons. And understandably so – Dr. Stern’s planetary exploration mission is on its way to Pluto after all, and what it’s expected to encounter is far more complex than what’s implied by the diminutive moniker of “dwarf planet” (which, oddly enough, was coined by Stern himself in 1990.)
I had a change to talk briefly with Dr. Stern on Friday, March 13 – which, incidentally, was the 85th anniversary of Pluto’s first announcement to the world – and got some insight from him on the mission and what we can expect from the upcoming flyby, as well as his views on the whole “planet/dwarf planet” thing. (And yes, it certainly does still matter!)
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On March 18, 2011, MESSENGER became the first human-made spacecraft to enter orbit around Mercury. Now almost four years, eight billion miles, and over 260,000 images later, MESSENGER is nearing the end of its operational life.
To commemorate the many achievements of the mission, scientists from NASA and the MESSENGER teams at the Johns Hopkins University Applied Physics Laboratory and the Carnegie Institution for Science are giving people around the world the opportunity to name five craters on Mercury — names which, once selected, will become official through the IAU!
33 years after his death, John Lennon’s name has been officially given to a crater on Mercury. Imagine that.
The 95 km (59 mile) wide Lennon crater is one of ten newly named craters on the planet, joining 114 other craters named since NASA’s MESSENGER spacecraft’s first Mercury flyby in January 2008.