Will Pluto be reissued its former status as a full-fledged planet? While it won’t necessarily be a topic of debate at next week’s meeting of the International Astronomical Union – the group in charge of, amongst other things, the official naming of all things extraterrestrial and thus the group responsible for voting Pluto off the planetary island three years ago – it may be the end result of new discoveries in the years ahead…the kinds of discoveries that make the most recent definitions of what signifies a “planet” hard to clarify.
Pluto, discovered in 1930 by Illinois native Clyde Tombaugh, was classified as the ninth planet until the IAU relegated it to dwarf planet status in 2006 due to some new “requirements” of planethood – notably, having enough gravitational influence to clear the path within one’s own orbit. (Illinois, by the way, officially claimed Pluto’s downgraded status as “unfair” and declared March 13, 2009 as “Pluto Day”.) This change was met with mixed reaction by the scientific community and concerned folks everywhere (at least those concerned about such things) and is still hotly debated in some circles.
At least in circles that debate such things hotly.
Anyway, some scientists – namely, Mark Sykes of Tucson’s Planetary Science Institute – think that the results of missions like NASA’s New Horizons spacecraft currently en route to Pluto will challenge the revised qualifications of planethood with their findings, perhaps demanding a re-evaluation. Sykes and others believe if an object directly orbiting a star is big enough for its own gravity to force it into a spherical shape, it should be a planet, regardless of how well it keeps its orbital room clean. Some say that Earth would have a hard time clearing the space around its orbit were it at Pluto’s distance from the sun due to the sheer length of time it takes to make the round trip. (248 years, to be exact.)
Of course, this definition would then have to promote some other worlds to official planetary status too…such as Ceres, an exceptionally large asteroid circling the sun between Mars and Jupiter, as well as many yet-to-be discovered bodies within the Kuiper Belt region even further out than Pluto. But, according to Sykes, the status of “planet” should be given according to our expanding scientific knowledge and not kept out-of-reach purely out of tradition.
“We are shaking off the last vestiges of the mythological view of planets as special objects in the sky – and the idea that there has to be a small number of them because they’re special.” – Mark Sykes, Planetary Science Institute, Tucson, AZ.
Regardless of its classification in science journals and textbooks, the New Horizons mission will be undoubtedly reveal fascinating information about Pluto and its moon, Charon. Even with powerful instruments like the Hubble Space Telescope, at 2.6 billion miles away they only appear as blurry points of light from here. Launched in January 2006, New Horizons will arrive at Pluto in 2015, do a flyby, and then soar into the Kuiper Belt and eventually out of the solar system entirely. The data it sends back will be the most detailed information we will have ever had about this most debated-over member of our solar system.
Planet or not, the results will definitely be exciting.