Have you ever broken up with someone only to later realize they were much cooler than you thought? That’s basically what’s going on with Pluto. To the dismay of everyone who dutifully learned the pneumonic device My Very Educated Mother Just Served Us Ninety-Nine Pizzas in elementary school, the “P” i
n Pizza, Pluto, was downgraded to a dwarf planet, and the official number of planets in our solar system decreased from nine to eight.
But in mid-July, 2015 NASA released images of Pluto that revealed its secret awesomeness. Mountains that would “stand up respectably against the Rocky Mountains,” according to John Spencer, planetary scientist on the New Horizons mission, appear to be made of ice – water ice. Although it was previously hypothesized that Pluto was covered in ice, it was believed to be the non-life-sustaining kind of ice.
A few other shocking revelations about our ex-planet resulted from the images which were obtained via a probe that traveled over 3.6 billion miles since Jan 19, 2006.
Has Pluto been holding out on us? Or did it get cooler after the breakup? “This is one of the youngest surfaces we’ve ever seen in the solar system,” said Geology, Geophysics and Imaging (GGI) team leader Jeff Moore of NASA’s Ames Research Center in Moffett Field, California. The surface may still be active today.
A recent article published by Phys.organd quoted here further muddied up the debate by taking into account a study Led by Kirby Runyon – a final year PhD student from the Department of Earth and Planetary Sciences at Johns Hopkins University. The team included scientists from the Southwest Research Institute (SwRI) in Boulder, Colorado; the National Optical Astronomy Observatory in Tuscon, Arizona; the Lowell Observatory in Flagstaff, Arizona; and the Department of Physics and Astronomy at George Mason University.
Their study – titled “A Geophysical Planet Definition”, which was recently made available on the Universities Space Research Association (USRA) website – addresses what the team sees as a need for a new definition that takes into account a planet’s geophysical properties. In other words, they believe a planet should be so-designated based on its intrinsic properties, rather than its orbital or extrinsic properties. From this more basic set of parameters, Runyon and his colleagues have suggested the following definition:
“A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters.”
As Runyon told Universe Today in a phone interview, “this definition is an attempt to establish something that is useful for all those involved in the study of planetary science, which has always included geologists:
“The IAU definition is useful to planetary astronomers concerned with the orbital properties of bodies in the solar system, and may capture the essence of what a ‘planet’ is to them. The definition is not useful to planetary geologists. I study landscapes and how landscapes evolve. It also kind of irked me that the IAU took upon itself to define something that geologists use too.
“The way our brain has evolved, we make sense of the universe by classifying things. Nature exists in a continuum, not in discrete boxes. Nevertheless, we as humans need to classify things in order to bring order out of chaos. Having a definition of the word planet that expresses what we think a planet ought to be, is concordant with this desire to bring order out of chaos and understand the universe.”
So is Pluto a planet? A dwarf planet? or a ball of ice? For myself I think I will join William Shatner and belive it is a planet!
For the full article please read more at: Phys.org
Feature image Courtesy of: NASA