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"Clearing the neighbourhood" is an informal description of part of the process of planet formation. Wikipedia does not have an article with this exact name. ... The final definition left the solar system with eight planets, pictured above (not to scale) Displays the remaining eight planets with the celestial bodies that have now been designated as dwarf planets. ... The accretion theory, in astrophysics, is a scientific theory of the formation of our Solar system. ...

The concept was used by the International Astronomical Union in its August 24, 2006, redefinition of the term "planet" as one of the criteria differentiating a planet from a dwarf planet; a planet is a body with sufficient mass to have "cleared the neighbourhood around its orbit".^[1] The IAU also explicitly stated that Pluto will now be considered a dwarf planet. Pluto has not cleared the neighborhood of its orbit (vis-à-vis Kuiper Belt Objects such as the Plutinos); the IAU's definition did not, however, explicitly state how this factor was to be measured in the general case, beyond that future decisions over borderline objects were to be made by "an IAU process", presumably in committee. Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The final definition left the solar system with eight planets, pictured above (not to scale) Displays the remaining eight planets with the celestial bodies that have now been designated as dwarf planets. ... Displays the remaining eight planets with the three new dwarf planets. ... Artists impression of Pluto together with its satellite Charon. ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... The Kuiper belt (KYE per) is an area of the solar system extending from within the orbit of Neptune (at 30 AU) to 50 AU from the sun, at inclinations consistent with the ecliptic. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ...

Details

The phrase refers to an orbiting body (a planet or protoplanet) "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or other bodies governed by its own gravitational influence. This latter restriction excludes objects whose orbits may cross but which will never collide with each other due to orbital resonance, such as Jupiter and the Trojan asteroids, Earth and 3753 Cruithne or Neptune and the Plutinos.^{[citation needed]} Displays the remaining eight planets with the three new dwarf planets. ... In cosmogony, a protoplanet is a quasi-planetoid which is slightly larger than a planetesimal and orbits within a solar nebulas protoplanetary discs. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. ... ... See also: Accretion (finance) Accretion is increase in size by gradual addition of smaller parts. ... A satellite is any object that orbits another object (which is known as its primary). ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Image of the Trojan asteroids in front of and behind Jupiter along its orbital path. ... Earth (often referred to as the earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... 3753 Cruithne (English crew-een-ya; Modern Irish crih-na) is an asteroid in orbit around the Sun. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ...

Steven Soter of the Department of Astrophysics, American Museum of Natural History, has written that "A heliocentric body with Λ > 1 [viz., a planet] has cleared a substantial fraction of small bodies out of its orbital neighborhood."^[2] Λ is a parameter proposed by Stern & Levison in 2002^[3] that measures the extent to which a body scatters smaller masses out of its orbital zone in a Hubble time, defined as The American Museum of Natural History is a landmark of Manhattans Upper West Side in New York, USA, at 79th Street and Central Park West. ...

Λ = kM²/P

where k is approximately constant and M and P are the scattering body's mass and orbital period, respectively. Two bodies are defined to share an orbital zone if their orbits cross a common radial distance from the primary, and their non-resonant periods differ by less than an order of magnitude. The order-of-magnitude similarity in period requirement excludes comets from the calculation, but the combined mass of the comets turn out to be negligible compared to the other small solar system bodies anyway so their inclusion would have little impact on the results.

The calculated parameters for major solar system bodies are:^[2]

Where mass and Λ were measured relative to Earth's mass and Λ, and where µ is the mass of the object divided by the mass of all the other objects in its orbital zone. Note: This article contains special characters. ... Adjective Venusian or (rarely) Cytherean (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... Earth (often referred to as the earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... For the Roman god, see Mars (mythology). ... 1 Ceres (seer-eez (key), IPA , Latin CerÄ“s) was the first asteroid to be discovered (indicated by the 1 in its name). ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Note: This article contains special characters. ... Adjective Uranian Atmospheric characteristics Atmospheric pressure 120 kPa (at the cloud level) Hydrogen 83% Helium 15% Methane 1. ... Adjective Neptunian Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... 2003 UB313 is a trans-Neptunian object (TNO) believed to be larger than the planet Pluto. ...

Controversy

Dr. Alan Stern, of the NASA New Horizons mission to Pluto, argues that Earth, Mars, Jupiter and Neptune have also not completely cleared their orbital neighbourhoods. Earth co-orbits with 10,000 near-Earth asteroids, and Jupiter has 100,000 Trojan asteroids in its orbital path. "If Neptune had cleared its zone, Pluto wouldn't be there," he has said.^[4] A contrary view is that having 'cleared the neighborhood' refers to an object being the dominant mass in its vicinity, e.g. Earth is many times more massive than all of the NEAs combined.^[2] This page may meet Wikipedias criteria for speedy deletion. ... NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... New Horizons is a NASA unmanned mission to fly by Pluto and its moons. ... Earth (often referred to as the earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... For the Roman god, see Mars (mythology). ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Adjective Neptunian Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earths orbit. ... As originally defined, Trojan asteroids have a semi-major axis between 5. ... Earth (often referred to as the earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ...

See also

• List of solar system objects by planetary discriminant

The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

References

1. ^ "The Final IAU Resolution on the definition of "planet" ready for voting", IAU, 24 August 2006. Retrieved on 2006-08-26.
2. ^ ^a b c Soter, Steven (2006-08-16). What is a Planet? (PDF). Retrieved on 2006-08-24. submitted to The Astronomical Journal, 16 August 2006
3. ^ Stern, S.A., Levison, H.F. (2002). "Regarding the criteria for planethood and proposed planetary classification schemes". Highlights of Astronomy 12: 205-213.
4. ^ Pluto vote 'hijacked' in revolt.