Pluto, a planet since 1930, got the boot because it didn't meet the new rules, which say a planet not only must orbit the sun and be large enough to assume a nearly round shape, but must “clear the neighborhood around its orbit.” That disqualifies Pluto, whose oblong orbit overlaps Neptune's, downsizing the solar system to eight planets from the traditional nine.
Astronomers from across the globe meeting in Prague adopted a new definition of “planet” Thursday. But the wording excluded Pluto, a member of the club of Solar System planets since its discovery in 1930. And some researchers criticized the definition as vague.
The decision follows years of growing frustration among scientists over the lack of a definition. New findings have made it increasingly obvious that traditional notions of “planet”—usually described as a large, round body orbiting a star—are too fuzzy to be of much use.
Some asteroids are almost as large and round as planets. And some planets are almost large and hot enough to be considered a type of star called a brown dwarf.
After tumultuous debate in Prague, the prestigious International Astronomical Union voted to define a planet as a celestial body that orbits the sun; is massive enough for its self-gravity to pull it into a ball shape; and “has cleared the neighbourhood around its orbit.”
Advocates of the wording argued that a planet must be the dominant object in its neighborhood.
This definition leaves eight planets in our Solar System, astronomers said: Mercury, Venus, Earth, Mars, Jupiter, Saturn, uranus and Neptune. Pluto is out because its oblong orbit overlaps with that of larger Neptune.
The decision at a conference of 2,500 astronomers was a stark shift from a week ago, when the organization leaders floated a proposal that would have reaffirmed Pluto’s planetary status and made planets of its largest moon and two other objects. That plan proved unpopular.
The guidelines ultimately adopted also didn’t sit well with researchers who still hold that Pluto is a planet. But they offered some solace by creating a category of “dwarf planet,” which includes Pluto. This classification is similar to the planet category but comprises those objects that have not cleared their orbital neighborhood.
The dwarf category is to include also the asteroid Ceres, considered a planet in the 1800s before it got demoted; and 2003 UB313, nicknamed Xena, an icy object slightly larger than Pluto.
“The classification doesn’t matter. Pluto—and all Solar System objects—are mysterious and exciting new worlds that need to be explored and better understood,” Louis Friedman, executive director of the Planetary Society in Pasadena, California, told the BBC News.
The decision settles a controversy over whether Xena would rise to planetary status, said Mike Brown of California Institute of Technology. Brown and colleagues announced Xena’s discovery last year. “I’m of course disappointed that Xena will not be the tenth planet, but I definitely support the IAU in this difficult and courageous decision,” said Brown. “It is scientifically the right thing to do.”
Not all astronomers agreed. Besides those who insist Pluto is a planet, others complain that the new definition is still muddled.
“What exactly is meant by a planet ‘clearing its neighborhood?’ said Hal Weaver of Johns Hopkins university in Maryland. Debate may also continue because, although the new definition is meant to distinguish planets from smaller bodies, it didn’t take on the question of how to separate super-large planets and stars. That question doesn’t affect the classification of planets in our Solar System, but will be relevant to some others.
The distant, ice-covered world is no longer a true planet, according to a new definition of the term voted on by scientists today.
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Virtual Solar System
Pluto's New Moons Named Nix, Hydra (June 23, 2006)
Pluto to Get Partners? New Definition of "Planet" Proposed (August 16, 2006)
"Whoa! Pluto's dead," said astronomer Mike Brown, of the California Institute of Technology in Pasadena, as he watched a Webcast of the vote. "There are finally, officially, eight planets in the solar system."
In a move that's already generating controversy and will force textbooks to be rewritten, Pluto will now be dubbed a dwarf planet.
But it's no longer part of an exclusive club, since there are more than 40 of these dwarfs, including the large asteroid Ceres and 2003 UB313, nicknamed Xena—a distant object slightly larger than Pluto discovered by Brown last year.
"We know of 44" dwarf planets so far, Brown said. "We will find hundreds. It's a very huge category."
A clear majority of researchers voted for the new definition at a meeting of the International Astronomical Union (IAU) in Prague, in the Czech Republic. The IAU decides the official names of all celestial bodies.
The tough decision comes after a multiyear search for a scientific definition of the word "planet." The term never had an official meaning before.
What Is a Planet Today?
According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.
Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons.
In addition, bodies that dominate their neighborhoods, "sweep up" asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto's orbit is somewhat untidy.
The International Astronomical Union decided that Pluto was no longer a planet. The reason is that while Pluto is round, orbits the sun, and has three moons, it has not cleared (via gravity) its own orbit of debris. Instead, they decided to classify it as a "dwarf planet".
See the details below.
RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet" [footnote 1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [footnote 2] , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects [footnote 3] except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
Footnote 1: The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Footnote 2: An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
Footnote 3: These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
RESOLUTION 6A
The IAU further resolves:
Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.
The Bible doesn't even aspect out different planets. till very those days, there had in no way been an attepmt to furnish a reliable definition as to what a planet is. the in problem-free words element that replaced into required to be a planet replaced into that it replaced right into a celestial body that orbited a favourite individual or human being gadget of stars (like binary stars) the project is that all the junk contained in the asteriod belt would qualify as planets, then, besides as arguably moons that orbit planets which orbit stars. various of skills were proposed. finally, the only which replaced into extensively huge-spread (even with the reality that no longer thoroughly) that disqualified Pluto replaced into that it ought to orbit round a favourite individual and in no way something else. Pluto's moon, Charon, is close adequate in length to Pluto itself that the moon does no longer orbit round Pluto. particularly, both easily one of them orbit round a level in area between them (in the route of Pluto, yet no longer everywhere interior Pluto). As such, Pluto and Charon both orbit that aspect which orbits the solar, particularly than Pluto itself orbitting the solar.
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Pluto, a planet since 1930, got the boot because it didn't meet the new rules, which say a planet not only must orbit the sun and be large enough to assume a nearly round shape, but must “clear the neighborhood around its orbit.” That disqualifies Pluto, whose oblong orbit overlaps Neptune's, downsizing the solar system to eight planets from the traditional nine.
http://www.cbsnews.com/stories/2006/08/24/tech/mai...
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Pluto no longer a planet
Aug. 24, 2006
Special to World Science
Updated Aug. 25
Astronomers from across the globe meeting in Prague adopted a new definition of “planet” Thursday. But the wording excluded Pluto, a member of the club of Solar System planets since its discovery in 1930. And some researchers criticized the definition as vague.
The decision follows years of growing frustration among scientists over the lack of a definition. New findings have made it increasingly obvious that traditional notions of “planet”—usually described as a large, round body orbiting a star—are too fuzzy to be of much use.
Some asteroids are almost as large and round as planets. And some planets are almost large and hot enough to be considered a type of star called a brown dwarf.
After tumultuous debate in Prague, the prestigious International Astronomical Union voted to define a planet as a celestial body that orbits the sun; is massive enough for its self-gravity to pull it into a ball shape; and “has cleared the neighbourhood around its orbit.”
Advocates of the wording argued that a planet must be the dominant object in its neighborhood.
This definition leaves eight planets in our Solar System, astronomers said: Mercury, Venus, Earth, Mars, Jupiter, Saturn, uranus and Neptune. Pluto is out because its oblong orbit overlaps with that of larger Neptune.
The decision at a conference of 2,500 astronomers was a stark shift from a week ago, when the organization leaders floated a proposal that would have reaffirmed Pluto’s planetary status and made planets of its largest moon and two other objects. That plan proved unpopular.
The guidelines ultimately adopted also didn’t sit well with researchers who still hold that Pluto is a planet. But they offered some solace by creating a category of “dwarf planet,” which includes Pluto. This classification is similar to the planet category but comprises those objects that have not cleared their orbital neighborhood.
The dwarf category is to include also the asteroid Ceres, considered a planet in the 1800s before it got demoted; and 2003 UB313, nicknamed Xena, an icy object slightly larger than Pluto.
“The classification doesn’t matter. Pluto—and all Solar System objects—are mysterious and exciting new worlds that need to be explored and better understood,” Louis Friedman, executive director of the Planetary Society in Pasadena, California, told the BBC News.
The decision settles a controversy over whether Xena would rise to planetary status, said Mike Brown of California Institute of Technology. Brown and colleagues announced Xena’s discovery last year. “I’m of course disappointed that Xena will not be the tenth planet, but I definitely support the IAU in this difficult and courageous decision,” said Brown. “It is scientifically the right thing to do.”
Not all astronomers agreed. Besides those who insist Pluto is a planet, others complain that the new definition is still muddled.
“What exactly is meant by a planet ‘clearing its neighborhood?’ said Hal Weaver of Johns Hopkins university in Maryland. Debate may also continue because, although the new definition is meant to distinguish planets from smaller bodies, it didn’t take on the question of how to separate super-large planets and stars. That question doesn’t affect the classification of planets in our Solar System, but will be relevant to some others.
The distant, ice-covered world is no longer a true planet, according to a new definition of the term voted on by scientists today.
Enlarge Photo
Email to a Friend
RELATED
Virtual Solar System
Pluto's New Moons Named Nix, Hydra (June 23, 2006)
Pluto to Get Partners? New Definition of "Planet" Proposed (August 16, 2006)
"Whoa! Pluto's dead," said astronomer Mike Brown, of the California Institute of Technology in Pasadena, as he watched a Webcast of the vote. "There are finally, officially, eight planets in the solar system."
In a move that's already generating controversy and will force textbooks to be rewritten, Pluto will now be dubbed a dwarf planet.
But it's no longer part of an exclusive club, since there are more than 40 of these dwarfs, including the large asteroid Ceres and 2003 UB313, nicknamed Xena—a distant object slightly larger than Pluto discovered by Brown last year.
"We know of 44" dwarf planets so far, Brown said. "We will find hundreds. It's a very huge category."
A clear majority of researchers voted for the new definition at a meeting of the International Astronomical Union (IAU) in Prague, in the Czech Republic. The IAU decides the official names of all celestial bodies.
The tough decision comes after a multiyear search for a scientific definition of the word "planet." The term never had an official meaning before.
What Is a Planet Today?
According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.
Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons.
In addition, bodies that dominate their neighborhoods, "sweep up" asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto's orbit is somewhat untidy.
The International Astronomical Union decided that Pluto was no longer a planet. The reason is that while Pluto is round, orbits the sun, and has three moons, it has not cleared (via gravity) its own orbit of debris. Instead, they decided to classify it as a "dwarf planet".
See the details below.
RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet" [footnote 1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [footnote 2] , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects [footnote 3] except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
Footnote 1: The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Footnote 2: An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
Footnote 3: These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
RESOLUTION 6A
The IAU further resolves:
Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.
The Bible doesn't even aspect out different planets. till very those days, there had in no way been an attepmt to furnish a reliable definition as to what a planet is. the in problem-free words element that replaced into required to be a planet replaced into that it replaced right into a celestial body that orbited a favourite individual or human being gadget of stars (like binary stars) the project is that all the junk contained in the asteriod belt would qualify as planets, then, besides as arguably moons that orbit planets which orbit stars. various of skills were proposed. finally, the only which replaced into extensively huge-spread (even with the reality that no longer thoroughly) that disqualified Pluto replaced into that it ought to orbit round a favourite individual and in no way something else. Pluto's moon, Charon, is close adequate in length to Pluto itself that the moon does no longer orbit round Pluto. particularly, both easily one of them orbit round a level in area between them (in the route of Pluto, yet no longer everywhere interior Pluto). As such, Pluto and Charon both orbit that aspect which orbits the solar, particularly than Pluto itself orbitting the solar.
Astronomers felt that it was too small to be considered a planet, even though it's own satellite Charon is half of Pluto's size.
It is still a planet but excluded at our solar system,it is called the dwarf
Cause apparently pluto was originally wrongly identified to be one by some dumbass.
It's too small...so now its an asteroid called 134340