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Faulkner observes that [[Comet Halley]], a short-period comet, is highly inclined and in a retrograde orbit. Comet Halley is, therefore, an important exception to the distinction. Faulkner ''also'' observes that short-period comets ''do not'' differ from long-period comets in composition.<ref name=Faulkner1/>

Faulkner observes that [[Comet Halley]], a short-period comet, is highly inclined and in a retrograde orbit. Comet Halley is, therefore, an important exception to the distinction. Faulkner ''also'' observes that short-period comets ''do not'' differ from long-period comets in composition.<ref name=Faulkner1/>

Cometary orbits are highly elliptical<ref name=Faulkner1/>, and some of these orbits are almost parabolic.</ref name=Weisstein/> ''Hyperbolic'' cometary orbits have never been observed.<ref name=Faulkner1/> This last observation is credited to Jan Oort himself.<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 2, 2008.</ref>

Cometary orbits are highly elliptical<ref name=Faulkner1/>, and some of these orbits are almost parabolic.<ref name=Weisstein/> ''Hyperbolic'' cometary orbits have never been observed.<ref name=Faulkner1/> This last observation is credited to Jan Oort himself.<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 2, 2008.</ref>

The more important point is that comets have a limited life span. After a few hundred perihelion passes at the Sun, a comet loses all of its tail-forming substance.<ref name=Arnett2>Arnett, Bill. "[http://www.nineplanets.org/comets.html Comets]." ''The <s>Nine</s> 8 Planets'', May 1, 2003. Accessed June 2, 2008.</ref> In addition, comets often destroy themselves in collision with planets and other bodies, or are ejected from the solar system entirely after making close flybys of [[Jupiter]] and other [[gas giant]]s.<ref name=Arnett2/><ref name=Faulkner1/><ref name=Faulkner2>[[Danny Faulkner|Faulkner, Danny]]. "[http://www.creationontheweb.com/content/view/1830 More problems for the 'Oort comet cloud']." ''Journal of Creation'' 15(2):11, August 2001. Accessed June 2, 2008.</ref>

The more important point is that comets have a limited life span. After a few hundred perihelion passes at the Sun, a comet loses all of its tail-forming substance.<ref name=Arnett2>Arnett, Bill. "[http://www.nineplanets.org/comets.html Comets]." ''The <s>Nine</s> 8 Planets'', May 1, 2003. Accessed June 2, 2008.</ref> In addition, comets often destroy themselves in collision with planets and other bodies, or are ejected from the solar system entirely after making close flybys of [[Jupiter]] and other [[gas giant]]s.<ref name=Arnett2/><ref name=Faulkner1/><ref name=Faulkner2>[[Danny Faulkner|Faulkner, Danny]]. "[http://www.creationontheweb.com/content/view/1830 More problems for the 'Oort comet cloud']." ''Journal of Creation'' 15(2):11, August 2001. Accessed June 2, 2008.</ref>