Home  ›  What are the requirements to be a planet?

What are the requirements to be a planet?

Written By Friday, 8 April 2022 Add Comment Edit

Formal definition of a planet in the context of the Solar Organization equally ratified by the IAU in 2006

This article is virtually the formal definition established in 2006. For other uses, run into Definition of planet.

The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System,[1] a planet is a celestial body that:

  1. is in orbit effectually the Sun,
  2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
  3. has "cleared the neighbourhood" around its orbit.

A non-satellite body fulfilling but the first two of these criteria (such as Pluto, which had hitherto been considered a planet) is classified every bit a dwarf planet. According to the IAU, "planets and dwarf planets are two distinct classes of objects" – in other words, "dwarf planets" are not planets. A non-satellite trunk fulfilling only the first criterion is termed a small Solar Organization body (SSSB). An alternate proposal included dwarf planets equally a subcategory of planets, only IAU members voted against this proposal. The determination was a controversial one, and has drawn both support and criticism from astronomers.

The IAU has stated that at that place are eight known planets in the Solar Organization. However, it is at present known that Mercury does not encounter criterion 2, just it is still universally considered to be a planet.[2] It has besides been argued that the definition is problematic because it depends on the location of the torso: if a Mars-sized body were discovered in the inner Oort cloud, it would not have enough mass to clear out a neighbourhood that size and see criterion three.[three]

The definition distinguishes planets from smaller bodies and is non applicable exterior the Solar Arrangement. To date, at that place is no accustomed definition of extrasolar planets, or exoplanets. In 2007, an IAU working grouping issued a position statement that proposes to distinguish exoplanets from chocolate-brown dwarfs on the footing of mass,[4] but there has been no IAU-wide resolution or vote associated with this position statement. A separate proposal to extend the IAU definition to exoplanets[v] has not been formally reviewed by the IAU.

Background [edit]

Plot of the positions of all known Kuiper belt objects (dark-green), ready against the outer planets (blue)

The process of new discoveries spurring a contentious refinement of Pluto's categorization echoed a contend in the 19th century that began with the discovery of Ceres on January one, 1801.[3] Astronomers immediately alleged the tiny object to be the "missing planet" between Mars and Jupiter. Within four years, nonetheless, the discovery of two more objects with comparable sizes and orbits had cast doubt on this new thinking. Past 1851, the number of "planets" had grown to 23 (the eight recognised today, plus fifteen between Mars and Jupiter), and it was clear that hundreds more would eventually be discovered. Astronomers began cataloguing them separately and began calling them "asteroids" instead of "planets".[6] With the discovery of Pluto by Clyde Tombaugh in 1930, astronomers considered the Solar Organisation to have nine planets, along with thousands of smaller bodies such as asteroids and comets. Pluto was thought to be larger than Mercury.

Tombaugh discovered Pluto while working at the Lowell Observatory founded by Percival Lowell, one of many astronomers who had theorized on the existence of the large trans-Neptunian object Planet X, and Tombaugh been searching for Planet 10 when he institute Pluto. Virtually immediately subsequently its discovery, notwithstanding, astronomers questioned whether Pluto could be Planet 10. Willy Ley wrote a column in 1956 titled "The Demotion of Pluto", stating that it "simply failed to live up to the accelerate publicity information technology received every bit 'Planet X' before its discovery. It has been a disappointment all forth, for it did not turn out to be what one could reasonably have expected".[7]

In 1978, Pluto's moon Charon was discovered. By measuring Charon's orbital period, astronomers could accurately calculate Pluto's mass for the outset fourth dimension, which they plant to be much smaller than expected.[8] Pluto's mass was roughly 1 twenty-fifth of Mercury's, making information technology by far the smallest planet, smaller even than the Globe's Moon, although it was still over x times as massive equally the largest asteroid, Ceres.

In the 1990s, astronomers began finding other objects at least every bit far abroad as Pluto, now known as Kuiper Belt objects, or KBOs.[9] Many of these shared some of Pluto's central orbital characteristics and are now called plutinos. Pluto came to be seen as the largest member of a new class of objects, and some astronomers stopped referring to Pluto every bit a planet.[3] Pluto'southward eccentric and inclined orbit, while very unusual for a planet in the Solar System, fits in well with the other KBOs. New York Metropolis'southward newly renovated Hayden Planetarium did not include Pluto in its exhibit of the planets when it reopened equally the Rose Middle for Globe and Space in 2000.[10]

Starting in 2000, with the discovery of at least three bodies (Quaoar, Sedna, and Eris) all comparable to Pluto in terms of size and orbit, it became clear that either they all had to exist called planets or Pluto would accept to be reclassified. Astronomers too idea information technology likely that more than objects equally big equally Pluto would be discovered, and the number of planets would first growing apace. They were also concerned about the classification of planets in other planetary systems. In 2006, the offset measurement of the volume of Eris erroneously (until the New Horizons mission to Pluto) showed it to be slightly larger than Pluto, and so was idea to exist as deserving of the status of "planet".[iii]

Because new planets are discovered infrequently, the IAU did not have whatsoever mechanism for their definition and naming. Later the discovery of Sedna, information technology set up a 19-member committee in 2005, with the British astronomer Iwan Williams in the chair, to consider the definition of a planet. It proposed three definitions that could be adopted:

Cultural
a planet is a planet if plenty people say it is;
Structural
a planet is large enough to form a sphere;
Dynamical
the object is large enough to cause all other objects to eventually leave its orbit.[11]

Some other commission, chaired by a historian of astronomy, Owen Gingerich, a historian and astronomer emeritus at Harvard University who led the commission which generated the original definition, and consisting of five planetary scientists and the science author Dava Sobel, was prepare to make a house proposal.[12]

Proposals [edit]

First draft proposal [edit]

Analogy of the draft proposal

The original proposal would take immediately added three planets, shown hither in a size comparison to Earth. Leftmost is Pluto (shown in lieu of Eris, which is about the same size), then Charon, Ceres, and Earth

The IAU published the original definition proposal on Baronial 16, 2006.[13] Its form followed loosely the second of iii options proposed by the original committee. It stated that:[13]

A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid trunk forces so that it assumes a hydrostatic equilibrium (near round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.

This definition would accept led to three more celestial bodies being recognized as planets, in improver to the previously accustomed nine:

  • Ceres, which had been considered a planet at the time of its discovery, only was subsequently treated as an asteroid
  • Charon, a moon of Pluto; the Pluto-Charon organization would have been considered a double planet
  • Eris, a body in the scattered disk of the outer Solar Organisation

A further twelve bodies, pending refinements of knowledge regarding their physical properties, were possible candidates to join the list under this definition. Some objects in this second list were more likely eventually to be adopted as 'planets' than others. Despite what had been claimed in the media,[14] the proposal did non necessarily exit the Solar System with only twelve planets. Mike Dark-brown, the discoverer of Sedna and Eris, has said that at to the lowest degree 53 known bodies in the Solar Organisation probably fit the definition, and that a consummate survey would probably reveal more 200.[15]

The definition would have considered a pair of objects to be a double planet system if each component independently satisfied the planetary criteria and the mutual eye of gravity of the organisation (known as the barycenter) was located outside of both bodies.[sixteen] Pluto and Charon would accept been the only known double planet in the Solar System. Other planetary satellites (like Earth and its moon) might be in hydrostatic equilibrium, but would still not have been divers every bit a component of a double planet, since the barycenter of the system lies inside the more massive celestial body (the World).

The twelve "candidate planets" that were possibilities for inclusion under the originally proposed definition. Note that all only the terminal three are trans-Neptunian objects. The smallest 3 (Vesta, Pallas, Hygeia) are in the asteroid chugalug.

The term "modest planet" would accept been abased, replaced past the categories "minor Solar System body" (SSSB) and a new classification of "pluton". The quondam would have described those objects underneath the "spherical" threshold. The latter would accept been applied to those planets with highly inclined orbits, large eccentricities and an orbital period of more than than 200 globe years (that is, those orbiting beyond Neptune). Pluto would accept been the prototype for this course. The term "dwarf planet" would have been available to draw all planets smaller than the eight "classical planets" in orbit around the Sunday, though would non have been an official IAU classification.[17] The IAU did not brand recommendations in the draft resolution on what separated a planet from a brown dwarf.[eighteen] A vote on the proposal was scheduled for August 24, 2006.[xiv]

Such a definition of the term "planet" could also take led to changes in nomenclature for the trans-Neptunian objects Haumea, Makemake, Sedna, Orcus, Quaoar, Varuna, 2002 TX300 , Ixion, and 2002 AW197 , and the asteroids Vesta, Pallas, and Hygiea.

On 18 Baronial the Committee of the Division of Planetary Sciences (DPS) of the American Astronomical Lodge endorsed the typhoon proposal.[19] The DPS Committee represents a small subset of the DPS members, and no resolution in support of the IAU definition was considered or approved by the DPS membership.

According to an IAU typhoon resolution, the roundness status generally results in the need for a mass of at to the lowest degree 5×10 20 kg, or bore of at least 800 km.[17] However, Mike Chocolate-brown claimed that these numbers are only correct for rocky bodies like asteroids, and that icy bodies like Kuiper Chugalug objects accomplish hydrostatic equilibrium at much smaller sizes, probably somewhere between 200 and 400 km in diameter.[15] It all depends on the rigidity of the material that makes upwards the body, which is in plow strongly influenced by its internal temperature. Assuming that Methone'southward shape reflects the balance between the tidal force exerted by Saturn and the moon'due south gravity, its tiny 3 km diameter suggests Methone is composed of icy fluff.[20] [21] The IAU'south stated radius and mass limit are not too far off from what every bit of 2019 is believed to be the approximate limit for objects beyond Neptune that are fully meaty, solid bodies, with Salacia (r = 423±xi km, one thousand = (0.492±0.007)×1021 km) and possibly 2002 MS4 (r = 400±12 km, one thousand unknown) being borderline cases both for the 2006 Q&A expectations and in more recent evaluations, and with Orcus existence just in a higher place the expected limit.[22]

Advantages [edit]

The proposed definition found support among many astronomers as it used the presence of a physical qualitative cistron (the object existence round) as its defining feature. Most other potential definitions depended on a limiting quantity (eastward.g., a minimum size or maximum orbital inclination) tailored for the Solar System. According to members of the IAU committee this definition did non use human being-made limits but instead deferred to "nature" in deciding whether or non an object was a planet.[23]

It likewise had the advantage of measuring an observable quality. Suggested criteria involving the nature of formation would have been more than likely to meet accepted planets later declassified every bit scientific understanding improved.[ commendation needed ]

Additionally, the definition kept Pluto as a planet. Pluto's planetary condition was and is fondly thought of past many, especially in the United states of america since Pluto was found past American astronomer Clyde Tombaugh, and the general public could have been alienated from professional astronomers; in that location was considerable uproar when the media last suggested, in 1999, that Pluto might be demoted, which was a misunderstanding of a proposal to catalog all trans-Neptunian objects uniformly.[24]

Criticism [edit]

The proposed definition was criticised as ambiguous: Astronomer Phil Plait and NCSE author Nick Matzke both wrote about why they thought the definition was not, in general, a good 1.[25] [26] It defined a planet as orbiting a star, which would take meant that any planet ejected from its star system or formed outside of one (a rogue planet) could non have been called a planet, even if information technology fit all other criteria. However, a similar state of affairs already applies to the term 'moon'—such bodies ceasing to be moons on being ejected from planetary orbit—and this usage has widespread acceptance. Some other criticism was that the definition did not differentiate between planets and brown dwarf stars. Any endeavour to analyze this differentiation was to be left until a subsequently appointment.

There had also been criticism of the proposed definition of double planet: at present the Moon is defined as a satellite of the Earth, but over time the Earth-Moon barycenter will drift outwards (see tidal dispatch) and could eventually become situated outside of both bodies.[27] This development would then upgrade the Moon to planetary status at that time, co-ordinate to the definition. The fourth dimension taken for this to occur, nevertheless, would be billions of years, long after many astronomers expect the Sunday to aggrandize into a cherry-red behemothic and destroy both Globe and Moon.[28]

In an 18 Baronial 2006 Science Fri interview, Mike Brown expressed dubiousness that a scientific definition was fifty-fifty necessary. He stated, "The analogy that I always like to employ is the word "continent". Y'all know, the word "continent" has no scientific definition ... they're just cultural definitions, and I think the geologists are wise to go out that one solitary and not try to redefine things and then that the word "continent" has a big, strict definition."[29]

On 18 August, Owen Gingerich said that correspondence he had received had been evenly divided for and against the proposal.[30]

Alternative proposal [edit]

The chronology of the events that took place in the 2006 IAU General Assembly are detailed in [1] (in Spanish).

According to Alan Boss of the Carnegie Establishment of Washington, a subgroup of the IAU met on August 18, 2006 and held a straw poll on the draft proposal: only 18 were in favour of it, with over 50 against. The l in opposition preferred an alternative proposal drawn up past Uruguayan astronomers Gonzalo Tancredi and Julio Ángel Fernández.[30]

(i) A planet is a celestial trunk that (a) is by far the largest object in its local population[1], (b) has sufficient mass for its self-gravity to overcome rigid body forces then that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) does non produce free energy by any nuclear fusion mechanism [3].

(2) According to point (i) the 8 classical planets discovered before 1900, which movement in well-nigh round orbits close to the ecliptic airplane are the simply planets of the Solar System. All the other objects in orbit effectually the Sunday are smaller than Mercury. We recognize that there are objects that fulfill the criteria (b) and (c) but not criterion (a). Those objects are defined as "dwarf" planets. Ceres also as Pluto and several other big Trans-Neptunian objects belong to this category. In contrast to the planets, these objects typically have highly inclined orbits and/or big eccentricities.

(3) All the other natural objects orbiting the Sun that do not fulfill whatever of the previous criteria shall exist referred to collectively equally "Modest Solar Arrangement Bodies".[4]

Definitions and clarifications
  1. The local population is the collection of objects that cross or closely approach the orbit of the body in consideration.
  2. This more often than not applies to objects with sizes above several hundred kilometers, depending on the material strength.
  3. This criterion allows the stardom between gas giant planets and brown dwarfs or stars.
  4. This class currently includes most of the Solar System asteroids, Virtually-Earth objects (NEOs), Mars-, Jupiter- and Neptune-Trojan asteroids, nigh Centaurs, about Trans-Neptunian Objects (TNOs), and comets.[31]

Under this proposal, Pluto would have been demoted to a dwarf planet.

Revised draft proposal [edit]

On 22 August 2006 the draft proposal was rewritten with ii changes from the previous draft.[32] [33] The first was a generalisation of the proper noun of the new course of planets (previously the draft resolution had explicitly opted for the term pluton), with a decision on the proper name to be used postponed. Many geologists had been critical of the choice of proper name for Pluto-similar planets,[34] being concerned about the term pluton, which has been used for years within the geological community to correspond a form of magmatic intrusion; such formations are adequately common balls of rock.[35] [36] Defoliation was idea undesirable due to the status of planetology as a field closely allied to geology.[37] Further concerns surrounded use of the word pluton as in major languages such equally French and Spanish, Pluto is itself called Pluton, potentially adding to defoliation.[ citation needed ]

The 2d change was a redrawing of the planetary definition in the instance of a double planet system. There had been a concern that, in extreme cases where a double body had its secondary component in a highly eccentric orbit, in that location could take been a migrate of the barycenter in and out of the primary torso, leading to a shift in the classification of the secondary body between satellite and planet depending on where the arrangement was in its orbit.[38] Thus the definition was reformulated so as to consider a double planet arrangement in existence if its barycenter lay exterior both bodies for a majority of the system'due south orbital period.[ citation needed ]

Later on on August 22, two open meetings were held which ended in an abrupt about-face on the bones planetary definition. The position of astronomer Julio Ángel Fernández gained the upper hand amid the members attending and was described as unlikely to lose its concord past August 24. This position would upshot in merely viii major planets, with Pluto ranking as a "dwarf planet".[39] The discussion at the get-go coming together was heated and lively, with IAU members in song disagreement with ane another over such bug every bit the relative merits of static and dynamic physics; the main sticking betoken was whether or not to include a body's orbital characteristics amid the definition criteria. In an indicative vote, members heavily defeated the proposals on Pluto-like objects and double planet systems, and were evenly divided on the question of hydrostatic equilibrium. The debate was said to be "still open", with private meetings being held ahead of a vote scheduled for the post-obit solar day.[xl]

At the second meeting of the twenty-four hours, following "secret" negotiations, a compromise began to emerge later the Executive Committee moved explicitly to exclude consideration of extra-solar planets and to bring into the definition a criterion concerning the authorization of a torso in its neighbourhood.[41]

Final draft proposal [edit]

The final, third typhoon definition proposed on 24 August 2006 read:

The IAU...resolves that planets and other bodies in the Solar Arrangement be divers into three distinct categories in the post-obit style:

(1) A planet [i] 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 information technology assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood effectually its orbit.

(two) A "dwarf planet" is a celestial trunk 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 [two], (c) has not cleared the neighbourhood effectually its orbit, and (d) is not a satellite.

(3) All other objects [3] orbiting the Sun shall be referred to collectively as "Small Solar Arrangement Bodies".

[i] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

[2] An IAU procedure will be established to assign deadline objects into either dwarf planet and other categories.

[3] These currently include most of the Solar System asteroids, near Trans-Neptunian Objects (TNOs), comets, and other modest bodies.

Analogy of the final proposal

Plenary session fence [edit]

Voting on the definition took place at the Assembly plenary session during the afternoon. Following a reversion to the previous rules on fifteen Baronial, as a planetary definition is a primarily scientific matter, every individual member of the Matrimony attending the Associates was eligible to vote. The plenary session was chaired past astronomer Jocelyn Bell Burnell.[42] During this session, IAU members cast votes on each resolution by raising yellow cards. A squad of students counted the votes in each department of the auditorium, and astronomer Virginia Trimble compiled and tallied the vote counts.[43]

Plenary session of the IAU General Assembly on August 24, 2006. Votes were cast by raising yellow cards.

The IAU Executive Committee presented four Resolutions to the Assembly, each concerning a different attribute of the fence over the definition.[44] Small-scale amendments were fabricated on the flooring for the purposes of description.

  • Resolution 5A constituted the definition itself equally stated higher up. There was much give-and-take among members nigh the appropriateness of using the expression "cleared the neighbourhood" instead of the earlier reference to "ascendant body", and about the implications of the definition for satellites. The Resolution was ultimately approved by a near-unanimous vote.
  • Resolution 5B sought to amend the above definition past the insertion of the word classical before the word planet in paragraph (one) and footnote [1]. This represented a pick betwixt having a set of three distinct categories of trunk (planet, "dwarf planet" and SSSB) and the opening of an umbrella of 'planets' over the first two such categories. The Resolution proposed the latter option; it was defeated convincingly, with simply 91[45] members voting in its favour.
  • Resolution 6A proposed a statement concerning Pluto: "Pluto is a dwarf planet past the above definition and is recognized as the prototype of a new category of trans-Neptunian objects." After a little quibbling over the grammar involved and questions of exactly what constituted a "trans-Neptunian object",[ citation needed ] the Resolution was canonical by a vote of 237–157, with 30 abstentions.[46] A new category of dwarf planet was thus established. It would exist named "plutoid" and more narrowly defined past the IAU Executive Committee on 11 June 2008.
  • Resolution 6B sought to insert an additional sentence at the end of the statement in 6A: "This category is to be called 'plutonian objects'." At that place was no debate on the question, and in the vote the proposed name was defeated by 186–183; a proposal to behave a re-vote was rejected. An IAU process was and so to be put in motility to decide the name for the new category.[45]

On a literal reading of the Resolution, "dwarf planets" are by implication of paragraph (1) excluded from the status of "planet". Use of the word planet in their title may, nevertheless, cause some ambiguity.

Final definition [edit]

The final definition, as passed on 24 August 2006 under the Resolution 5A of the 26th General Assembly, is:[47] [48]

Illustration of the outcome of the vote

The IAU...resolves that planets and other bodies, except satellites, in the Solar Arrangement be defined into three distinct categories in the following fashion:

(1) A planet [i] is a celestial trunk that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces and so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(ii) A "dwarf planet" is a angelic body that (a) is in orbit around the Sun, (b) has sufficient mass for its cocky-gravity to overcome rigid body forces so that information technology assumes a hydrostatic equilibrium (virtually round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects [three], except satellites, orbiting the Sunday shall be referred to collectively every bit "Pocket-size Solar System Bodies".

Footnotes:

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
[two] An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

[three] These currently include virtually of the Solar Arrangement asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized equally the prototype of a new category of Trans-Neptunian Objects[ane].

Footnote:

[ane] An IAU process will exist established to select a name for this category.

The IAU also resolved that "planets and dwarf planets are 2 distinct classes of objects", meaning that dwarf planets, despite their proper noun, would not be considered planets.[45]

Closing issues [edit]

Substance [edit]

Alan Stern, the atomic number 82 scientist on NASA's robotic mission to Pluto, contended that Earth, Mars, Jupiter, and Neptune have non fully cleared their orbital zones, simply similar Pluto. Earth orbits with 10,000 near-Globe asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path. Stern has asserted: "If Neptune had cleared its zone, Pluto wouldn't be there."[49]

Some astronomers counter this opinion by maxim that, far from not having cleared their orbits, the major planets completely control the orbits of the other bodies inside their orbital zone. Although Jupiter does coexist with a large number of small bodies in its orbit (the Trojan asteroids), these bodies only be in Jupiter'south orbit considering they are in the sway of the planet's huge gravity. Earth accretes or ejects about-Earth asteroids on million-twelvemonth time scales, thereby immigration its orbit. Similarly, Pluto may cross the orbit of Neptune, but Neptune long ago locked Pluto and its attendant Kuiper belt objects, chosen plutinos, into a three:2 resonance (i.e., they orbit the Sun twice for every 3 Neptune orbits). Since the orbits of these objects are entirely dictated past Neptune's gravity, Neptune is therefore gravitationally dominant.[50]

On June eleven, 2008, the IAU appear that the subcategory of dwarf planets with trans-Neptunian orbits would be known as "plutoids". In an accompanying press release, the IAU said that:[51]

Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their cocky-gravity to overcome rigid body forces and then that they assume a hydrostatic equilibrium (near-spherical) shape, and that accept not cleared the neighbourhood around their orbit.

This subcategory includes Pluto, Haumea, Makemake and Eris.

Some aspects of the definition are as yet difficult to apply exterior the Solar System. Techniques for identifying extrasolar objects by and large cannot determine whether an object has "cleared its orbit", except indirectly via an orbit-immigration criterion. The wording of the 2006 definition is heliocentric in its use of the give-and-take Sun instead of star or stars, and is thus not applicable to the numerous objects which have been identified in orbit around other stars. A dissever "working" definition for extrasolar planets was, however, recommended past a working group of the IAU in 2003[52] and includes the benchmark: "The minimum mass/size required for an extrasolar object to exist considered a planet should exist the same as that used in the Solar System."[53]

Process [edit]

The final vote was criticized because of the relatively small percentage of the 9000-strong IAU membership who participated. Likewise the fact that most members do not nourish the General Assemblies, this lack was also due to the timing of the vote: the terminal vote was taken on the terminal day of the x-day consequence, afterward many participants had left or were preparing to leave. Many astronomers were also unable or chose non to make the trip to Prague and, thus, cast no vote. Only 424 astronomers were present for the vote, which is less than 5% of the astronomer customs.[49] However, sampling 400 representative members out of a population of ix,000 statistically yields a result with good accurateness (confidence interval better than 5%).[54] Astronomer Marla Geha has antiseptic that non all members of the Union were needed to vote on the classification outcome: only those whose piece of work is directly related to planetary studies.[55]

Touch on [edit]

The determination generated cultural and societal implications, affecting the "manufacture of astronomical artifacts and toys."[56] Most educational books that included the definition were printed after 2006. The decision was important enough to prompt the editors of the 2007 edition of the World Book Encyclopedia to hold off press until a final result had been reached.[56]

Popular civilisation [edit]

The affect of the revised definition, particularly the modify in the status of Pluto, has been reflected in popular culture. A number of musical contributions have commemorated the alter:

  • "Planet X" (1996), vocal by Christine Lavin. A good-natured protest against suggestions that Pluto is non a planet.[ citation needed ]
  • "Pluto" (1998), song past 2 Skinnee J'due south. An impassioned defence force of Pluto'south status as a planet.[ citation needed ]
  • Thing a Week, August 25, 2006 podcast by Jonathan Coulton. Featured a song "I'm Your Moon", from Charon'south point of view, about Pluto being reclassified as a dwarf planet.[ citation needed ]
  • "Bring Dorsum Pluto" (2007), song by Aesop Rock on the anthology None Shall Laissez passer. Hip-hop song supporting Pluto's status as the ninth planet in the Solar System.[ citation needed ]
  • "Pluto" (2009), song by Robbie Fulks, role of his release "fifty-vc. Doberman." About Pluto's reclassification, remembered as a 9th planet from the times of the vocalist's youth, and re-presents Pluto equally an unforgotten monarch of the Kuiper Belt.[ citation needed ]
  • "Ode to Pluto" is the final track on Terra Lumina's cocky-titled debut album, mentioning the change of classification.[ citation needed ]
  • Pluto'south demotion is alluded to in "The Lonesome Friends of Science" on John Prine's The Tree of Forgiveness, in which the planets (including non-real Vulcan) are anthropomorphized, and Pluto is "uninvited to the interplanetary dance."[ commendation needed ]

Plutoed [edit]

The verb to pluto (preterite and past participle: plutoed) was coined in the aftermath of the 2006 IAU decision. In January 2007, the American Dialect Society chose plutoed as its 2006 Discussion of the Twelvemonth, defining to pluto equally "to demote or devalue someone or something, every bit happened to the former planet Pluto when the Full general Assembly of the International Astronomical Matrimony decided Pluto no longer met its definition of a planet."[57] [58]

Society president Cleveland Evans stated the reason for the organization's selection of plutoed: "Our members believe the peachy emotional reaction of the public to the demotion of Pluto shows the importance of Pluto equally a proper noun. Nosotros may no longer believe in the Roman god Pluto, simply nosotros still take a sense of connection with the former planet".[59]

Run into besides [edit]

  • Immigration the neighbourhood
  • Fusor (astronomy)
  • Geophysical planet definition
  • Listing of Solar System objects
  • List of former planets
  • Pocket-size planet
  • Planemo
  • Small-scale Solar Arrangement body

References [edit]

  1. ^ Exoplanets are addressed in a 2003 position statement issued by a now-defunct IAU Working Group on Extrasolar Planets. Still, this position statement was never proposed as an official IAU resolution and was never voted on by IAU members.
  2. ^ Sean Solomon, Larry Nittler & Brian Anderson, eds. (2018) Mercury: The View subsequently MESSENGER. Cambridge Planetary Science series no. 21, Cambridge University Press, pp. 72–73.
  3. ^ a b c d Gibor Basri; Michael E. Brown (2006). "Planetesimals to Brown Dwarfs: What is a Planet?" (PDF). Annual Review of Earth and Planetary Sciences. 34: 193–216. arXiv:astro-ph/0608417. Bibcode:2006AREPS..34..193B. doi:10.1146/annurev.earth.34.031405.125058. S2CID 119338327. Retrieved 2008-08-04 .
  4. ^ Boss, Alan P.; Butler, R. Paul; Hubbard, William B.; Ianna, Philip A.; Kürster, Martin; Lissauer, Jack J.; Mayor, Michel; Meech, Karen J.; Mignard, Francois; Penny, Alan J.; Quirrenbach, Andreas; Tarter, Jill C.; Vidal-Madjar, Alfred (2007). "Working Group on Extrasolar Planets". Transactions of the International Astronomical Union. 26A: 183–186. Bibcode:2007IAUTA..26..183B. doi:x.1017/S1743921306004509.
  5. ^ Margot, Jean-Luc (2015-10-xv). "A Quantitative Criterion for Defining Planets". The Astronomical Journal. 150 (6): 185. arXiv:1507.06300. Bibcode:2015AJ....150..185M. doi:ten.1088/0004-6256/150/half dozen/185. S2CID 51684830.
  6. ^ Soter, Steven (2007). "What Is a Planet?". Scientific American. 296 (one): 34–41. arXiv:astro-ph/0608359. Bibcode:2007SciAm.296a..34S. doi:10.1038/scientificamerican0107-34. PMID 17186831. Archived from the original on 2007-ten-xiii. Retrieved 2007-01-11 .
  7. ^ Ley, Willy (Baronial 1956). "The Demotion of Pluto". For Your Information. Milky way Science Fiction. pp. 79–91.
  8. ^ Buie, Marc W.; Grundy, William M.; Young, Eliot F.; Young, Leslie A.; Stern, Southward. Alan (2006). "Orbits and Photometry of Pluto's Satellites: Charon, S/2005 P1, and South/2005 P2". The Astronomical Journal. 132 (1): 290–298. arXiv:astro-ph/0512491. Bibcode:2006AJ....132..290B. doi:10.1086/504422. S2CID 119386667.
  9. ^ Much Ado virtually Pluto Archived 2008-01-25 at the Wayback Auto plutopetition.com
  10. ^ Pluto at 75: Still Crazy After All These Years Infinite.com
  11. ^ Stephen Eales, Prospect, p.p.31-34 (May 2007)
  12. ^ Eales, op. cit.
  13. ^ a b "The IAU draft definition of "planet" and "plutons"" (Press release). International Astronomical Union. 2006-08-16. Retrieved 2008-08-xvi .
  14. ^ a b Gareth Melt (2006-08-xvi). "Nine no longer: Panel declares 12 planets". Boston Earth . Retrieved 2006-08-16 .
  15. ^ a b Chocolate-brown, Mike (2006). "How Many Planets Are In that location?". Caltech . Retrieved 2006-08-sixteen .
  16. ^ Robert Roy Britt (2006). "Nine Planets Become 12 with Controversial New Definition". Space.com . Retrieved 2006-08-sixteen .
  17. ^ a b "Typhoon Resolution 5 for GA-XXVI: Definition of a Planet". International Astronomical Union. 2006. Archived from the original on August 22, 2006. Retrieved 2006-08-16 .
  18. ^ "Planet Definition" Questions & Answers Sheet". International Astronomical Matrimony. 2006. Archived from the original on August 22, 2006. Retrieved 2006-08-16 .
  19. ^ "Planetary Scientists Support Proposed Redefinition Of A Planet". SpaceDaily. 2006. Retrieved 2006-08-19 .
  20. ^ Thomas, P. C.; Burns, J. A.; Tiscareno, Yard. S.; Hedman, M. M.; Helfenstein, P. (2013). "Saturn's Mysterious Arc-Embedded Moons: Recycled Fluff?" (PDF). 44th Lunar and Planetary Scientific discipline Briefing. p. 1598. Retrieved 2013-05-21 .
  21. ^ Battersby, S. (2013-05-17). "Saturn's egg moon Methone is made of fluff". New Scientist . Retrieved 2013-05-21 .
  22. ^ Grundy, W.M.; Noll, K.South.; Buie, M.Westward.; Benecchi, S.D.; Ragozzine, D.; Roe, H.M. (2019). "The Mutual Orbit, Mass, and Density of Transneptunian Binary Gǃkúnǁʼhòmdímà ((229762) 2007 UK126 )". Icarus. 334: 30–38. doi:10.1016/j.icarus.2018.12.037. S2CID 126574999. Archived (PDF) from the original on vii April 2019.
  23. ^ Robert Roy Britt (2006). "Ix Planets Become 12 with Controversial New Definition". Space.com . Retrieved 2006-08-19 .
  24. ^ Pearson education (2006). "The Flap over Pluto". infoplease.com . Retrieved 2006-08-19 .
  25. ^ Phil Plait (2006). "Congratulations! It's a planet!". Bad Astronomy . Retrieved 2006-08-18 .
  26. ^ Nick Matzke (2006). "Wherein I argue emotionally well-nigh the definition of "planet"". The Panda'due south Thumb. Archived from the original on 2006-09-08. Retrieved 2006-08-18 .
  27. ^ Robert Roy Britt (2006). "Moon Mechanics: What Really Makes Our World Go 'Round". Space.com. Archived from the original on 2010-08-22. Retrieved 2010-08-24 .
  28. ^ Robert Roy Britt (2006). "Earth'south moon could become a planet". CNN.
  29. ^ Ira Flatow and Mike Brown (2006-08-18). "Pluto'south Planet Condition / Cord Theory". Scientific discipline Friday. National Public Radio. Archived from the original on 2006-08-xxx. Retrieved 2006-08-22 .
  30. ^ a b Britt, Robert Roy (2006-08-18). "Pluto May Get Demoted Subsequently All". Space.com. Retrieved 2006-08-24 .
  31. ^ "Details Sally on Programme to Demote Pluto". 2006. Retrieved 2006-08-xviii .
  32. ^ Günther Wuchterl (2006-08-22). "The IAU Commission Presents Today in Prague the new Proposals for the Definition of Planet". Retrieved 2008-08-04 .
  33. ^ Günther Wuchterl (2006-08-23). "The IAU's Definition of Planet develops further – Draft c". Retrieved 2008-08-04 .
  34. ^ "Star-gazers puzzled by Pluto". Independent Online. 2006. Retrieved 2006-08-18 .
  35. ^ "Geologists Force Astronomers To Rethink Pluto Plan". 2006. Archived from the original on 2007-05-17. Retrieved 2006-08-18 .
  36. ^ Elise Kleeman (2006). "Planet, pluton or stone?". Pasadena Star News. Archived from the original on 2007-09-28. Retrieved 2006-08-20 .
  37. ^ Geoff Brumfiel (2006-08-21). "Plutons, planets and dwarves : Geologists and astronomers wrangle over words". Nature News. doi:10.1038/news060821-4. S2CID 128414918.
  38. ^ Phil Plait (2006-08-15). "Congratulations! It's a planet!" (blog) . Retrieved 2008-08-04 .
  39. ^ Overbye, Dennis (2006-08-22). "Pluto Seems Poised to Lose Its Planet Status". New York Times.
  40. ^ "Astronomers divided over 'planet' definition". Deutsche Presse-Agentur. 2006-08-22. Archived from the original on 2006-08-thirty.
  41. ^ Tresch Fienberg, Richard (2006-08-22). "The Day We Lost Pluto". Heaven & Telescope.
  42. ^ Hogan, Jenny (2008-08-24). "Diary of a planet'due south demise". Nature.
  43. ^ "Pluto in perspective". Orange County Register. 2006-09-01.
  44. ^ IAU Full general Assembly Newspaper, 24 Baronial 2006
  45. ^ a b c "IAU 2006 General Assembly: Result of the IAU Resolution votes" (Press release). International Astronomical Matrimony (News Release – IAU0603). 2006-08-24. Retrieved 2007-12-31 . ( orig link Archived 2007-01-03 at the Wayback Machine)
  46. ^ "IAU General Associates Paper, 25 August 2006" (PDF). IAU . Retrieved 2014-07-03 .
  47. ^ "IAU 2006 General Assembly: Resolutions v and 6" (PDF). IAU. 2006-08-24.
  48. ^ "IAU 2006 General Assembly: Effect of the IAU Resolution votes" (Press release). Prague: IAU (News Release – IAU0603). August 24, 2006. Retrieved 2008-08-04 .
  49. ^ a b Paul Rincon (2006-08-25). "Pluto vote 'hijacked' in revolt". BBC. Retrieved 2008-08-01 .
  50. ^ Michael E. Brown (2006). "The Eight Planets". Caltech . Retrieved 2007-02-21 .
  51. ^ "Plutoid called as name for Solar System objects like Pluto" (Press release). Paris: International Astronomical Union (News Release – IAU0804). 2008-06-11. Retrieved 2008-06-eleven .
  52. ^ Boss, Alan P; Butler, R. Paul; Hubbard, William B; Ianna, Philip A; Kürster, Martin; Lissauer, Jack J; Mayor, Michel; Meech, Karen J; Mignard, Francois; Penny, Alan J; Quirrenbach, Andreas; Tarter, Jill C; Vidal-Madjar, Alfred (2007). "Definition of a planet". Proceedings of the International Astronomical Union. 1: 183–186. Bibcode:2007IAUTA..26..183B. doi:x.1017/S1743921306004509.
  53. ^ "Position argument on the Definition of a "Planet"". Working Grouping on Extrasolar Planets (IAU). 2003-02-28. Archived from the original on 2006-09-16. Retrieved 2008-08-04 .
  54. ^ Margot, Jean-Luc (2006). "What makes a planet?". UCLA . Retrieved 2013-08-28 .
  55. ^ "A Passion For Pluto". thenation.com. Retrieved 2006-09-13 .
  56. ^ a b Dennis Overbye (2006-08-24). "Pluto is demoted to 'dwarf planet'". NYTimes . Retrieved 2006-08-27 .
  57. ^ ""Plutoed" Voted 2006 Word of the Year" (PDF). American Dialect Order. January 5, 2007. Retrieved 2007-01-07 .
  58. ^ "Pluto'due south revenge: 'Word of the Year' laurels". CNN. January seven, 2007. Retrieved 2007-01-20 .
  59. ^ "'Plutoed' called as '06 Word of the Year". Associated Press. Jan 8, 2007. Retrieved 2007-01-ten .

External links [edit]

  • IAU 2006 General Assembly: Result of the IAU Resolution votes International Astronomical Spousal relationship official site.
  • IAU 2006 General Associates: video-records of the discussion and of the terminal vote on the Planet definition.
  • Planet Definition Questions & Answers Sheet, International Astronomical Matrimony Official Site
  • Q&A: The IAU'southward Proposed Planet Definition Q&A article on the new definition from Infinite.com
  • Dwarf planet discoverer Mike Brown explains the concept backside the new definition
  • Cronología de los hechos relativos a la Definición de Planeta adoptada por la Asamblea de la Unión Astronómica Internacional

foxsuchoson.blogspot.com

Source: https://en.wikipedia.org/wiki/IAU_definition_of_planet

0 Response to "What are the requirements to be a planet?"

Post a Comment

Subscribe to: Post Comments (Atom)

Iklan Atas Artikel

Iklan Tengah Artikel 1

Iklan Tengah Artikel 2

Iklan Bawah Artikel