Definition of "Planet" Forever Lost... Nov 22, 2006 0:06:13 GMT -6
Post by Chicago Astronomer Joe on Nov 22, 2006 0:06:13 GMT -6
Why Planets Will Never Be Defined
Before the dust even settled after the Great Pluto War at the International Astronomical Union (IAU)'s General Assembly in Prague, one thing became clear: There will never be an accepted scientific definition for the term "planet."
Rather than crafting an acceptable definition, the IAU alienated members, put the group's authority in jeopardy and fueled schisms among astronomers on theoretical grounds and even nationality.
And the whole affair was scientifically pointless, many astronomers say.
The controversial planet-definition resolution, passed Aug. 24 in a vote of just 424 IAU members, will not stand as worded. Some 300 astronomers have pledged not to use it, and many others say it must be redone to eliminate contradictions. It will be reworked, at the least, and possibly overturned at the 2009 IAU General Assembly in Rio de Janeiro, Brazil.
Meanwhile, the debate—which the IAU limited to defining round things in our solar system—was a neighborhood nomenclature brawl amid a universal war of words. Any terminology that might be relevant to our little solar system will be laughably inadequate if applied across the galaxy.
During 2006, the tally of known extrasolar planets surpassed 200, and the range of sizes and setups illustrates why a universal definition is impossible in light of the fact that scientists are sharply divided on what to call Pluto.
The debate over what constitutes a planet flared up after the 1990 discovery of the first round objects orbiting another star. The three so-called pulsar planets are about the same size as Earth. They are often forgotten in discussions about exoplanets. Some astronomers don't see them as planets at all, because they orbit a fast-spinning, dead star that cannot support life.
Other worlds several times the mass of Jupiter float freely in space; they have no host star. Are they planets? Other oddities abound.
"It is a little-known fact that nearly 25 percent of the known extrasolar planets are in binary- or multiple-star systems," said Stephen Kortenkamp , a research associate at the University of Maryland. "That further complicates the notion of creating a universal definition of planet."
One day during what Kortenkamp calls the Great Pluto War, he browsed his dictionary. "I see lots of words that have multiple definitions, depending on the context in which they are used," he told me back then. "I don't see why the word 'planet' can't be treated the same way."
The Great Pluto War alienated many of the roughly 10,000 professional astronomers around the world who did not have a chance to cast a vote. It also created "two major rifts" among astronomers, said David Morrison, an astronomer at NASA's Ames Research Center who was among the few who did vote.
"Most important was a rift between astronomers who study physical properties of objects and those who study orbits (dynamics)," Morrison told me. "The dynamicists dominated at the IAU, and many of them would not accept any definition that was based solely on physical properties such as size."
"The second division was along national lines," Morrison explained. "Some astronomers seemed irritated by perceived American domination of the process. Some felt, with considerable justification in my opinion, that some Americans astronomers defended Pluto as a planet in large part because an American had discovered it. As in so many other international contexts, there can be reaction against perceived American arrogance."
Full story here: www.space.com/scienceastronomy/061121_exoplanet_definition.html
A new definition of "round body" must be created, considering some objects that are round outside our system don't orbit a sun.
With all them inflated degrees out there, I'm sure some one can define this conundrum