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Topic: Definition of planet


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  PLANET - Definition
Note: The term planet was first used to distinguish those stars which have an apparent motion through the constellations from the fixed stars, which retain their relative places unchanged.
The inferior planets are Mercury and Venus, which are nearer to the sun than is the earth; the superior planets are Mars, the asteroids, Jupiter, Saturn, Uranus, and Neptune, which are farther from the sun than is the earth.
Primary planets are those which revolve about the sun; secondary planets, or moons, are those which revolve around the primary planets as satellites, and at the same time revolve with them about the sun.
www.hyperdictionary.com /dictionary/planet   (277 words)

  
 New planet definition sparks furore - space - 25 August 2006 - New Scientist Space
The new planet definition that relegates Pluto to "dwarf planet" status is drawing intense criticism from astronomers.
That is because the definition stipulates that to be a planet, an object must have cleared the neighbourhood around its orbit.
A better definition would say a planet is an object that orbits a star and is large enough to be spherical, but is not large enough to be a brown dwarf — a "failed" star with between about 13 and 75 times the mass of Jupiter — or a star, he says.
space.newscientist.com /article/dn9846-new-planet-definition-sparks-furore.html   (1004 words)

  
  The IAU draft definition of 'planet' and 'plutons'
Owen Gingerich, the Chair of the Planet Definition Committee says: "In July we had vigorous discussions of both the scientific and the cultural/historical issues, and on the second morning several members admitted that they had not slept well, worrying that we would not be able to reach a consensus.
According to the new draft definition, two conditions must be satisfied for an object to be called a "planet." First, the object must be in orbit around a star, while not being itself a star.
The draft "Planet Definition" Resolution will be discussed and refined during the General Assembly and then it (plus four other Resolutions) will be presented for voting at the 2nd session of the GA 24 August between 14:00 and 17:30 CEST.
www.eurekalert.org /pub_releases/2006-08/iau-tid081506.php   (914 words)

  
 A New Solar System - Explore the Cosmos | The Planetary Society
Planets seemed intuitively obvious, and if more were discovered somewhere in the universe, both professionals and lay people confidently assumed that they will know one when they see one.
The true planets, argue proponents of the eight-planet solar system, are naturally distinguishable from the plethora of large and small objects at the edge of the solar system, and our definition of "planet" should reflect that.
Similar to the Planet Definition Committee's proposal, the resolution states that "a planet is a celestial body that (a) is in orbit around the Sun and (b) has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
www.planetary.org /explore/topics/pluto/new_solarsystem.html   (2772 words)

  
 SPACE.com -- Nine Planets Become 12 with Controversial New Definition
Planet sizes are shown to scale but their orbital distances are not to scale.
Pluto would remain a planet and its moon Charon would be reclassified as a planet.
Given all the nuances in the definition, a dozen other objects would be put on an IAU list of "candidate planets" which, upon further study, might bring the tally of planets in our solar system to 24.
www.space.com /scienceastronomy/060816_planet_definition.html   (1478 words)

  
 Scientists: Pluto not a planet - Space.com- msnbc.com
This lineup shows the 12 planets that were proposed last week, with a wedge of the sun at far left.
Pluto and its moon Charon, which would both have been planets under the initial definition proposed Aug. 16, now get demoted because they are part of a sea of other objects that occupy the same region of space.
definition and is recognized as the prototype of a new category of trans-Neptunian objects," states the approved resolution.
www.msnbc.msn.com /id/14489259   (1198 words)

  
 The IAU draft definition of 'planet' and 'plutons'
If the definition is approved by the astronomers gathered 14-25 August 2006 at the IAU General Assembly in Prague, our Solar System will include 12 planets, with more to come: eight classical planets that dominate the system, three planets in a new and growing category of “plutons” – Pluto-like objects – and Ceres.
Owen Gingerich, the Chair of the Planet Definition Committee says: “In July we had vigorous discussions of both the scientific and the cultural/historical issues, and on the second morning several members admitted that they had not slept well, worrying that we would not be able to reach a consensus.
According to the new draft definition, two conditions must be satisfied for an object to be called a “planet.” First, the object must be in orbit around a star, while not being itself a star.
www.physorg.com /news74917943.html   (1159 words)

  
 Planet
Smaller terrestrial planets lose most of their atmospheres because of this accretion, but the lost gases can be replaced by outgassing from the mantle and from the subsequent impact of comets.
A planet's year depends on its distance from the Sun; the farther a planet is from the Sun, not only the longer the distance it must travel, but also the slower its speed, as it is less affected by the Sun's gravity.
GJ 436 which are approximately Neptune-sized, and a planet orbiting Gliese 876 that is estimated to be about 6 to 8 times as massive as the Earth and is probably rocky in composition.
schools-wikipedia.org /wp/p/Planet.htm   (3411 words)

  
 The IAU draft definition of "planet" and "plutons" | Press Releases | IAU
News Release - IAU0601: The IAU draft definition of "planet" and "plutons"
If the definition is approved by the astronomers gathered 14-25 August 2006 at the IAU General Assembly in Prague, our Solar System will include 12 planets, with more to come: eight classical planets that dominate the system, three planets in a new and growing category of "plutons" - Pluto-like objects - and Ceres.
The draft "Planet Definition" Resolution will be discussed and refined during the General Assembly and then it (plus four other Resolutions) will be presented for voting at the 2nd session of the GA 24 August between 14:00 and 17:30 CEST.
www.iau.org /public_press/news/release/iau0601   (1084 words)

  
 Planet Definition - Astronomy 2006 - IAU XXVIth General Assembly
The ongoing work on an IAU Resolution to scientifically define the meaning of the concept „planet“ is of particular interest to the public.
The boundary between planets and other solar system objects has never been defined and the recent discoveries of new objects in the solar system has made it necessary for the IAU to address this issue.
The decision process and a draft Resolution for the Definition of a Planet will be published in the conference newspaper during the first week of the General Assembly.
www.astronomy2006.com /planet-definition.php   (159 words)

  
 LiveScience.com Blogs » Blog Archive » 300 Astronomers Will Not Use New Planet Definition
However, the word “planet” has cultural, historical, and social meaning and as such requires much broader discussion and consensus than those required for the naming of astronomical bodies.’ “The CSEPR is currently examining the nature of scientific authority, and its use and misuse in issues of fundamental concern to the public.
A planet may be a gas planet, a rocky planet, an ice planet, a small planet, a big planet.
It is fundamentally incorrect to use “planet” in a label for non-planets (unless of course you are preceding planet with “Non-”.) Pluto is a “Non-Planet”, not a “Dwarf Planet”.
www.livescience.com /blogs/2006/08/31/300-astronomers-wont-use-new-planet-definition   (3117 words)

  
 Pluto may lose planet status - smh.com.au
According to Professor Basri's definition, a planet must orbit a star, not another planet, and it must be round.
Under his definition, the 900-kilometre asteroid Ceres, discovered in 1801, would become a planet, as would the Kuiper-belt objects of Varuna, discovered in 2000, and Quaoar.
A New York planetarium in 1999 did not include Pluto in its display of planets, and the IAU was forced to deny rumours that year it would delist Pluto.
www.smh.com.au /articles/2003/03/09/1047144868646.html   (539 words)

  
 Xinhua - English   (Site not responding. Last check: )
According to the new rules for a planet adopted at an International Astronomical Union meeting in Prague, Pluto doesn't make the grade for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a...
The definition, which Ecker described as "carefully refined" with much compromise after considerable discussion, came in line with the contemporary observation that has been changing the understanding of planetary system.
If a larger category of "planet" is created, we can leave open the possibility to discover and define other types of planets, he said.
news.xinhuanet.com /english/2006-08/25/content_5003955.htm   (361 words)

  
 Definition of planet - Definition, explanation
Although planets are the principal component of the solar system other than the Sun, a definition of what a planet actually is, is surprisingly elusive.
Eventually these "planets" numbered in their thousands, and were referred to as minor planets before being eventually given their own separate classification, asteroids, letting the concept of planet survive with little modification.
Ultimately, there is probably no real need for a strict definition of what a planet is, with convention and history instead playing the major role in determining what is considered a planet and what is not.
www.calsky.com /lexikon/en/txt/d/de/definition_of_planet.php   (1349 words)

  
 Buie: Definition of a Planet   (Site not responding. Last check: )
Rule 2: A planet must be large enough to have a shape determined by gravity and not the strength of its material (usually this means it is spherical).
This could be a planet that was once in orbit around a star but was stripped away and left to wander in the cold and dark between the stars.
If this definition were to be accepted and still useful (and used) 10,000 years from now by our distant descendents (or any other beings for that matter), then I would consider this definition to be a success.
www.lowell.edu /users/buie/pluto/planetdefn.html   (642 words)

  
 The Final IAU Resolution on the definition of "planet" ready for voting | Press Releases | IAU
Resolution 5A is the principal definition for the IAU usage of "planet" and related terms.
(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) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.
www.iau.org /public_press/news/release/iau0602   (1033 words)

  
 Definition of planet
Pluto does not qualify as a planet under this definition, and the Solar System is thus considered to have eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
California Institute of Technology suggested that a "planet" should be redefined as "any body in the solar system that is more massive than the total mass of all of the other bodies in a similar orbit." The eight planets over that mass limit would be referred to as "major planets".
According to the current definition, Earth and its Moon, since their barycenter lies within the Earth, are excluded from double planet status.
schools-wikipedia.org /wp/d/Definition_of_planet.htm   (3669 words)

  
 What is a Planet
After examining a number of definitions from dictionaries and encyclopedias, a fair summary of the "cultural" definition of "planet" seems to be something like "an object resembling the planets in the Solar System, which is orbiting a star".
As regards the definition of "planet", of course, the other question is whether one is willing to use a purely mass-based definition, or must consider cosmogony and circumstance as well.
Given the cultural understanding of "planet" it would seem at first that, in a discussion of circumstance, this case cannot be included in the definition of "planet".
astro.berkeley.edu /~basri/defineplanet/whatsaplanet.htm   (6565 words)

  
 planet - definition of planet from YourDictionary.com
The known planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
terrestrial: Understanding Mercury, and the forces that have shaped it, is fundamental to understanding the terrestrial planets and their evolution.
X: This so-called Planet X would be a gas ball up to five times the size of Earth, according to some predictions.
www.yourdictionary.com /planet   (461 words)

  
 The Space Review: Inside the planet definition process (page 1)
The Planet Definition Committee—four planetologists, two other astronomers (including one historian of astronomy), and a writer—had, after surprisingly short deliberations this summer, “unanimously” settled on the radical idea that all bodies massive enough to force themselves into an approximately spherical shape should be called planets, regardless of their role and place in the solar system.
Pluto’s satellite Charon would also become a planet (because the barycenter of the pair resides in the open space between their bodies) and the same would be happening to the asteroid Ceres, which was once considered a planet but had lost that designation over a hundred years ago.
According to that text a planet “is by far the largest object in its local population”, the latter being defined in a footnote as “the collection of objects that cross or close [sic] approach the orbit of the body in consideration”.
www.thespacereview.com /article/703/1   (2366 words)

  
 Definition of 'planet' expected in September - USATODAY.com
All the newfound worlds — there are several known now — were until recently smaller than Pluto, but they are round and orbit the sun, two characteristics that had for centuries been sufficient for the implicit definition of planet.
But the dozen or so astronomers on the committee could not agree whether to define planet strictly by mass, or to consider orbital characteristics as well as how and where a planet formed, among other things.
Last fall they argued over possibly putting adjectives in front of planet, such as gas giant, terrestrial, asteroidal and perhaps even traditional or historic to grandfather Pluto into the family of "regular" worlds.
www.usatoday.com /tech/science/space/2006-06-08-planet-defined_x.htm   (931 words)

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