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Line 1: − + − + − [http://cfa-www.harvard.edu/iau/lists/TNOs.html List of known KBOs]+ − + + − John Gribbin, ''Companion to the Cosmos'' (Little, Brown & Company, 1996)+ + + + + + + + + + + + + + + + + + + + + + + + + +
Expansion and clarification regarding comet origin controversy
'''The Kuiper belt''' is a region of space out beyond the orbit of [[Neptune]]. It was discovered by Gerard Kuiper. Objects in the Kuiper belt are called Kuiper belt objects (KBOs). Sometimes, comets from the Kuiper belt fall into the inner portion of the Solar System due to gravitational disturbances.
The '''Kuiper Belt''', or the '''Edgeworth-Kuiper Belt''', is a zone immediately beyond the orbit of [[Neptune]] and includes all objects in orbit around the [[Sun]] that remain between 30 AU and 50 AU distant from the Sun. It is the largest single collection of known [[Trans-Neptunian Objects]].<ref name=Jewitt>Jewitt, David. "[http://www.ifa.hawaii.edu/faculty/jewitt/kb.html Kuiper Belt]." University of Hawaii, n.d. Accessed June 20, 2008.</ref> The name is in honor of [[Gerard P. Kuiper]], the [[astronomy|astronomer]] who in 1951 first hypothesized its existence and its possible role as the host and source of short-period [[comet]]s.<ref name=Arnett>Arnett, Bill. "[http://www.nineplanets.org/kboc.html The Kuiper Belt and the Oort Cloud]." ''The <s>Nine</s> 8 Planets'', March 18, 2007. Accessed June 20, 2008.</ref><ref name=Hamilton>Hamilton, Calvin J. "[http://www.solarviews.com/eng/kuiper.htm The Kuiper Belt]." ''Views of the Solar System'', 2001. Accessed June 20, 2008.</ref> Occasional references mention [[Kenneth E. Edgeworth]] as having hypothesized an outlying source of short-period comets in 1943, before Gerard P. Kuiper published his paper.<ref name=sol>"[http://www.solstation.com/stars/kuiper.htm Edgeworth-Kuiper Belt and Dust Disk]." Sol Company, 2008. Accessed June 20, 2008.</ref><ref name=Orrery>"[http://www.harmsy.freeuk.com/kuiper.html The Kuiper Belt]." ''SpaceTech's Orrery'', n.d. Accessed June 20, 2008.</ref>
==External Links==
The definition of the Kuiper belt appears somewhat confused. Some astronomers appear to use the terms "Kuiper belt object" (KBO) and "trans-Neptunian object" (TNO) to refer to the same class of objects.<ref name=Jewitt/><ref name=Johnston>Johnston, William Robert. "[http://www.johnstonsarchive.net/astro/tnos.html Trans-Neptunian Objects]." ''The Johnston Archive'', October 1, 2007. Accessed June 20, 2008.</ref> This is not correct. A ''trans-Neptunian object'' is any object having a [[semi-major axis]] higher than that of [[Neptune]]. A ''Kuiper belt object'' is an object that remains between 30 AU and 55 AU distant from the Sun. Thus the Kuiper belt is a ''subset'' of trans-Neptunian objects.<ref name=Faure>Faure, Gérard. "[http://www.astrosurf.com/aude/map/us/AstFamilies2004-05-20.htm Description of the System of Asteroids as of May 20, 2004]," Richard Miles, trans. Accessed June 20, 2008.</ref>
The conflation of the terms TNO and KBO persists, with some astronomers using the term "classic KBO" to refer to any object lying within the strict bounds of the Kuiper belt.<ref name=Johnston/>
==References==
== Recognition ==
Technically the first object belonging to the Kuiper belt to be discovered was [[Pluto]] in 1930. Next to be discovered was [[Charon]], the [[moon]] of Pluto, in 1978.<ref name=Wilson>Wilson, G. "[http://userpages.umbc.edu/~gwilson/kuiper.html The Kuiper Belt]." n.d. Accessed June 20, 2008.</ref> However, the first discovery that caused the astronomical community to recognize the Kuiper belt as a real collection of bodies in the [[solar system]] was that of [[1992 QB1]] in August of 1992.<ref name=Wilson/>
== Composition ==
The number of objects that the Kuiper belt contains is confused. Jewitt estimates more than 70,000<ref name=Jewitt/>, but independent corroboration of this number is singularly lacking. Parker<ref name=Parker>Parker, Joel W. "News and Announcements." ''[http://www.boulder.swri.edu/ekonews/issues/past/n027/html/index.html Distant EKO's: The Kuiper Belt Electronic Newsletter]'', issue 27, January 2003. Accessed June 20, 2003.</ref> counted 651 as of January of 2003. Furthermore, Jewitt states that the 70,000 objects he estimates have diameters of 100 km or greater. Wilson<ref name=Wilson/> calls these "super-comets" thus emphasizing that they are far larger than true comets.
Delsanti and Jewitt<ref name=Delsanti>Delsanti, Audrey, and Jewitt, David. "[http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf The Solar System Beyond the Planets]." 2006. Accessed June 20, 2008.</ref> now estimate that the total mass of all objects in the Kuiper belt cannot be more than one-tenth the mass of the [[Earth]]. The primary basis of this new estimate is that Kuiper belt objects are now known to be much brighter than originally supposed, and brighter than the members of the Jupiter family of [[comet]]s.
The composition of these objects is believed similar to that of the [[Dwarf Planet|dwarf planets]] [[Pluto]] and [[Eris]].
== The Short-Comet Theory ==
Short-period comets include all those having periods less than 200 years.<ref name=Weisstein>Weisstein, Eric W. "[http://scienceworld.wolfram.com/astronomy/OortCloud.html Oort Cloud]." ''Eric Weisstein's World of Astronomy'', 1996-2007. Accessed June 2, 2008</ref><ref name=Faulkner1>[[Danny Faulkner|Faulkner, Danny]]. "[http://www.answersingenesis.org/docs/4108.asp Comets and the Age of the Solar System]." TJ, 11(3):264-273, December 1997. Accessed June 2, 2008.</ref> Almost all of these are prograde, and their orbits are only slightly inclined to the ecliptic.<ref name=Brown>[[Walt Brown|Brown, Walt]]. "[http://www.creationscience.com/onlinebook/Comets4.html#wp1387242 How Comets Move]." ''[[In the Beginning: Compelling Evidence for Creation and the Flood]], June 16, 2008. Accessed June 20, 2008.</ref>
The near-universal consensus among secular astronomers is that the Kuiper belt is the source of short-period comets. But the evidence from current observation poses many problems for this theory. First, as Delsanti and Jewitt have admitted, the total mass of the Kuiper belt is severely limited—to ten percent of the mass of the earth, including the masses of [[Pluto]] and its moon [[Charon]]. Second, the objects known to exist in the Kuiper belt (however many there may be) have diameters of 100 km or greater, far greater than the diameter of any comet head. Third, even the 70,000 objects that Jewitt estimates that the Kuiper belt contains is far fewer than the billion or so objects that would actually be required to supply short-period comets over the presumed 4.5-billion-year age of the solar system.<ref name=Newton>Newton, Robert. "[Kuiper Belt Objects: Solution to Short-period Comets]?" ''TJ'' 16(2):15-17, August 2002. Accessed June 20, 2008.</ref> Third, some of these objects, like Pluto, are in orbits that are severely inclined to the ecliptic, totally unlike the short-period comets to which they are supposed to give rise.
Champions of the short-comet theory contend that actual short-period comets result from fragmentation of the large KBOs or else are simply too dim for Earth-based telescopes to observe.
== Observation and exploration ==
The only observation of the Kuiper belt or of the objects within it has been by Earth observatories and the [[Hubble Space Telescope]]. However, the [[New Horizons mission]], launched on January 19, 2006, will arrive in the Belt in 2015, first to explore Pluto and its moons, and then to explore at least one other KBO. The Panoramic Survey Telescope and Rapid Response System (Pan-Starrs) survey project<ref name=PanStarrs>"[http://pan-starrs.ifa.hawaii.edu/public/ Pan-Starrs Home]."</ref> should be completed by then, and its findings might assist New Horizons mission planners in selecting their next target after Pluto.<ref name=Weisstein>Weisstein, Eric W. "[http://scienceworld.wolfram.com/astronomy/OortCloud.html Oort Cloud]." ''Eric Weisstein's World of Astronomy'', 1996-2007. Accessed June 2, 2008</ref>
== References ==
{{reflist|2}}
== Related Links ==
*[http://cfa-www.harvard.edu/iau/lists/TNOs.html List of known trans-Neptunian objects]. Harvard University.
*Lisle, Jason. "[http://www.answersingenesis.org/docs2005/0805tenth_planet.asp The 'tenth planet' is discovered]." AiG–USA August 5, 2005. Accessed June 20, 2008.
*[[Jonathan Sarfati|Sarfati, Jonathan]]. "[http://www.answersingenesis.org/creation/v25/i3/comets.asp Comets-portents of doom or indicators of youth?]." ''Creation'' 25(3):36–40, June 2003. Accessed June 20, 2008.
== See Also ==
* [[Astronomy]]
{{Solarsystem}}
{{Solarsystem}}
[[Category:Astronomy]]
[[Category:Astronomy]]