Changes

¹The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

¹The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

²An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

²An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

³These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies. <ref>"[http://www.iau.org/iau0602.423.0.html IAU0602: the Final IAU Resolution on the Definition of 'Planet' Ready for Voting]," ''International Astronomical Union'', 2005. Accessed January 14, 2008.</ref> }}

³These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.<ref>"[http://www.iau.org/iau0602.423.0.html IAU0602: the Final IAU Resolution on the Definition of 'Planet' Ready for Voting]," ''International Astronomical Union'', 2005. Accessed January 14, 2008.</ref> }}

Under those rather strict criteria, Pluto does not qualify. For that reason, Pluto is no longer considered a planet. It shares the new "dwarf planet" category with Eris, Ceres, Haumea and Makemake. <ref>http://www.iau.org/public_press/news/detail/iau0807/</ref>

Under those rather strict criteria, Pluto does not qualify. For that reason, Pluto is no longer considered a planet. It shares the new "dwarf planet" category with Eris, Ceres, Haumea and Makemake.<ref>http://www.iau.org/public_press/news/detail/iau0807/</ref>

But Walter T. Brown, of the Center for Scientific Creation, noted in an exclusive interview with the National Creationism Examiner, that the IAU leadership took up that resolution when only ''four percent of its membership'' could attend. Evidently the IAU makes no rules as to what portion of its voting membership constitutes a quorum. (Why they don't simply use the e-mail version of Roberts' ''Rules of Order'', no one has asked them.)

But Walter T. Brown, of the Center for Scientific Creation, noted in an exclusive interview with the National Creationism Examiner, that the IAU leadership took up that resolution when only ''four percent of its membership'' could attend. Evidently the IAU makes no rules as to what portion of its voting membership constitutes a quorum. (Why they don't simply use the e-mail version of Roberts' ''Rules of Order'', no one has asked them.)

== Physical characteristics ==

== Physical characteristics ==

[[File:Frozen carbon monoxide pluto.jpg|thumb|350px|right|False-color image of Pluto showing frozen lake of [[carbon monoxide]] (green) in the western lobe of Tombaugh Regio (the "heart shape").]]Pluto has a density of 2,030 kg/m³, comparable to that of [[Ceres]]. It also has a brownish-red color, like that of [[iron]] rust. Significantly, [[Charon]], its innermost [[moon]], does not have that color.

[[File:Frozen carbon monoxide pluto.jpg|thumb|350px|right|False-color image of Pluto showing frozen lake of [[carbon monoxide]] (green) in the western lobe of Tombaugh Regio (the "heart shape").]]Pluto has a density of 2,030&nbsp;kg/m³, comparable to that of [[Ceres]]. It also has a brownish-red color, like that of [[iron]] rust. Significantly, [[Charon]], its innermost [[moon]], does not have that color.

Conventional astronomers attribute the rust color of Pluto to a class of substances called "tholins" (literally, "mud-colored stuff") forming from the bombardment of hypothesized atmospheric constituents by ultraviolet radiation. But Walter T. Brown has another theory: the substance giving Pluto its rust color really ''is'' iron rust. Which, he says, formed far closer to the [[Sun]] than Pluto now orbits. (More on that below.)

Conventional astronomers attribute the rust color of Pluto to a class of substances called "tholins" (literally, "mud-colored stuff") forming from the bombardment of hypothesized atmospheric constituents by ultraviolet radiation. But Walter T. Brown has another theory: the substance giving Pluto its rust color really ''is'' iron rust. Which, he says, formed far closer to the [[Sun]] than Pluto now orbits. (More on that below.)

The [[Hydroplate theory]] of the [[Great Flood]] says that Pluto, Charon, and all the other moons of Pluto formed from material ejected from earth in the early stage of the Flood. As this material passed beyond the earth, it fell out of Earth's gravitational influence. Then and only then could it accrete. Pluto simply received a higher proportion of iron-containing rock than did Charon.

The [[Hydroplate theory]] of the [[Great Flood]] says that Pluto, Charon, and all the other moons of Pluto formed from material ejected from earth in the early stage of the Flood. As this material passed beyond the earth, it fell out of Earth's gravitational influence. Then and only then could it accrete. Pluto simply received a higher proportion of iron-containing rock than did Charon.

The two bodies were also moving through an environment with a large quantity of gas in it. Pluto especially acquired a vast atmosphere (by one account, more than 11,000 km in extent). The atmospheric pressure would set up a steep gradient between the day and night sides of Pluto. In addition, Pluto and Charon could act like solar sails, gaining momentum from light pressure. All these influences gave those bodies extra momentum to push them into a close encounter with a gas giant, most likely Jupiter. The two bodies, and probably the four other bodies that would form the rest of the system, passed close to Jupiter, then fell south of the ecliptic. That explains the argument of perihelion greater than 90 degrees.

The two bodies were also moving through an environment with a large quantity of gas in it. Pluto especially acquired a vast atmosphere (by one account, more than 11,000&nbsp;km in extent). The atmospheric pressure would set up a steep gradient between the day and night sides of Pluto. In addition, Pluto and Charon could act like solar sails, gaining momentum from light pressure. All these influences gave those bodies extra momentum to push them into a close encounter with a gas giant, most likely Jupiter. The two bodies, and probably the four other bodies that would form the rest of the system, passed close to Jupiter, then fell south of the ecliptic. That explains the argument of perihelion greater than 90 degrees.

The highly eccentric orbit of the Pluto-Charon system around the sun, is typical of the orbits of the largest trans-Neptunian objects.

The highly eccentric orbit of the Pluto-Charon system around the sun, is typical of the orbits of the largest trans-Neptunian objects.

Pluto is its prime target, but mission planners are considering plans to study at least one other [[Kuiper belt]] object.<ref name=Jenner>Jenner, Lynn. "[http://www.nasa.gov/mission_pages/newhorizons/main/index.html NASA - New Horizons]." [[National Aeronautics and Space Administration|NASA]], October 9, 2007. Accessed July 3, 2008.</ref><ref name=Talbert>[http://www.nasa.gov/mission_pages/newhorizons/main/index.html New Horizons official site], ed. Tricia Talbert/NASA. First accessed 10 July 2015.</ref>

Pluto is its prime target, but mission planners are considering plans to study at least one other [[Kuiper belt]] object.<ref name=Jenner>Jenner, Lynn. "[http://www.nasa.gov/mission_pages/newhorizons/main/index.html NASA - New Horizons]." [[National Aeronautics and Space Administration|NASA]], October 9, 2007. Accessed July 3, 2008.</ref><ref name=Talbert>[http://www.nasa.gov/mission_pages/newhorizons/main/index.html New Horizons official site], ed. Tricia Talbert/NASA. First accessed 10 July 2015.</ref>

On 15 January 2015, New Horizons began its final approach to Pluto. On 14 July of 2015, New Horizons passed directly through the Plutonian system and took the best photographs of it to date. Mission controllers expect New Horizons to transmit its thousands of high-resolution photographs and other data by the end of 2016.

On 15 January 2015, New Horizons began its final approach to Pluto. On 14 July 2015, New Horizons passed directly through the Plutonian system and took the best photographs of it to date. Mission controllers expect New Horizons to transmit its thousands of high-resolution photographs and other data by the end of 2016.

New Horizons now awaits further orders to alter its course to reconnoiter any other Kuiper Belt object it might be able to reach.

New Horizons now awaits further orders to alter its course to reconnoiter any other Kuiper Belt object it might be able to reach.