SkipCaptcha
305
edits
Changes
Jump to navigation
Jump to search
Line 33:
Line 33: − + − + − == Discovery ==+ − + Line 53:
Line 53: − == The dwarf planet controversy ==+ Line 92:
Line 92: − + + + + + − == 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/m<sup>3</sup>, 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.
Sporadic edits to heading
:''This article is about the [[dwarf planet]]. For the Roman god, see [[Pluto (god)]].''
:''This article is about the [[dwarf planet]]. For the Roman god, see [[Pluto (god)]].''
'''134340 Pluto''' is a [[dwarf planet]] in the Kuiper belt of the outer solar system. It was discovered in 1930 by American astronomer Clyde Tombaugh. It is orbited by a large moon called Charon as well as by two smaller moons, Nix and Hydra. Charon was discovered in 1978.
'''134340 Pluto''' is a [[dwarf planet]] in the Kuiper belt of the outer solar system. It was discovered in 1930 by [[American]] astronomer [[Clyde W. Tombaugh|Clyde Tombaugh]]. It is orbited by a large moon called Charon as well as by two smaller moons, Nix and Hydra. Charon was discovered in 1978.
Pluto was classified as one of the nine major planets until 2006. Pluto is the Roman god of the underworld. In 2015 the U.S. spacecraft ''New Horizons'' passed through the Plutonian system.
Pluto was recognized as one of the nine major planets from its discovery. A group of astronomers from the [[International Astronomical Union]] reclassified it as a [[dwarf planet]] in 2006 after the discovery of [[Eris]]. Not all planetary scientists agree with this reclassification as there is still controversy over the [[International Astronomical Union | IAU's]] own definition of what qualifies as a planet. Pluto is the Roman god of the underworld. In 2015 the U.S. spacecraft ''New Horizons'' passed through the Plutonian system.
= Discovery =
Pluto was discovered by [[Clyde W. Tombaugh]] on February 18, 1930 at the Lowell Observatory in Flagstaff, Arizona. Tombaugh's daughter Annette proposed the name of that object: Pluto.
Pluto was discovered by [[American]] astronomer [[Clyde W. Tombaugh]] on February 18, 1930 at the Lowell Observatory in Flagstaff, Arizona. Tombaugh's daughter Annette proposed the name of that object: Pluto. Pluto remains one of the only planets ever to have been discovered or named by [[American|Americans]] although the [International Astronomical Union|IAU]] now claims it is a [[dwarf planet]]
Tombaugh was searching for "Planet X," a planet beyond [[Neptune]] that was believed to be influencing Neptune's orbit. Percival Lowell, founder of the observatory where Tombaugh worked, had calculated possible sky positions for Planet X based on observations of Neptune's orbit. However, Tombaugh did not make use of Lowell's calculations. Instead, he used the observatory's telescope to photograph the opposition point to the sun every night for a year, thus conducting a full sky survey of the Zodiac.
Tombaugh was searching for "Planet X," a planet beyond [[Neptune]] that was believed to be influencing Neptune's orbit. Percival Lowell, founder of the observatory where Tombaugh worked, had calculated possible sky positions for Planet X based on observations of Neptune's orbit. However, Tombaugh did not make use of Lowell's calculations. Instead, he used the observatory's telescope to photograph the opposition point to the sun every night for a year, thus conducting a full sky survey of the Zodiac.
In 2015 the U.S. spacecraft ''New Horizons'' passed through the Plutonian system. ''New Horizons'' found many signs that are ''not'' consistent with the conventional favored theory of Pluto's origin. Pluto has mountains that have not eroded. That suggests the body is active. Pluto also has a frozen lake of carbon monoxide that no one has yet been able to explain.
In 2015 the U.S. spacecraft ''New Horizons'' passed through the Plutonian system. ''New Horizons'' found many signs that are ''not'' consistent with the conventional favored theory of Pluto's origin. Pluto has mountains that have not eroded. That suggests the body is active. Pluto also has a frozen lake of carbon monoxide that no one has yet been able to explain.
= The [[dwarf planet]] controversy =
[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon [[Charon]]. NASA image]]
[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon [[Charon]]. NASA image]]
The discovery of [[Eris]], a scatter-disk body 27% more massive than Pluto, caused a controversy concerning what does, and what does not, constitute a [[planet]]. If Pluto were to retain its historical designation of "planet," then Eris would also qualify. But Eris was held not to qualify because it was in a neighborhood with multiple other objects, a situation similar to those of similar bodies in the [[asteroid]] belt, namely [[Ceres]] and [[Eris]].
The discovery of [[Eris]], a scatter-disk body 27% more massive than Pluto, caused a controversy concerning what does, and what does not, constitute a [[planet]]. If Pluto were to retain its historical designation of "planet," then Eris would also qualify. But Eris was held not to qualify because it was in a neighborhood with multiple other objects, a situation similar to those of similar bodies in the [[asteroid]] belt, namely [[Ceres]] and [[Eris]].
Brown suspects the IAU wanted to demote Pluto, because Pluto violates, by its very existence, every conventional theory of planetary origin.
Brown suspects the IAU wanted to demote Pluto, because Pluto violates, by its very existence, every conventional theory of planetary origin.
=[[Earth]] and [[Mars]] as [[dwarf planet|dwarf planets]] under the current [[International Astronomical Union]] definition=
== [[Earth]] and [[Mars]] as [[dwarf planet|dwarf planets]] under the current [[International Astronomical Union]] definition ==
According to Number 1 (c) and 2 (c) of the [[International Astronomical Union|IAU]] definition, also [[Earth]] and [[Mars]] wouldn't be planets because they haven't "cleared" their orbits as several asteroids are in their respective orbits, these asteroids are also called "quasi-moons" of Earth and Mars. The IAU precluded this possibility by arbitrarily listing the earth and mars as planets in spite of the current definition (see the quote in the above section: ''"<sup>1</sup>The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune."'').
According to Number 1 (c) and 2 (c) of the [[International Astronomical Union|IAU]] definition, also [[Earth]] and [[Mars]] wouldn't be planets because they haven't "cleared" their orbits as several asteroids are in their respective orbits, these asteroids are also called "quasi-moons" of Earth and Mars. The IAU precluded this possibility by arbitrarily listing the earth and mars as planets in spite of the current definition (see the quote in the above section: ''"<sup>1</sup>The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune."'').
This, however, calls into question the "''scientific''" basis of downgrading Pluto to a dwarf plant as this conflicting standard(of confirming [[earth]] and [[mars]] as planets while classifying Pluto as a dwarf planet) suggests it is merely the '''''opinion''''' of the IAU that Pluto is not a planet <ref>https://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf ''International Astronomical Union'', 2005. Accessed February 9, 2022</ref>
This, however, calls into question the "''scientific''" basis of downgrading Pluto to a dwarf plant as this conflicting standard(of confirming [[earth]] and [[mars]] as planets while classifying Pluto as a dwarf planet) suggests it is merely the '''''opinion''''' of the IAU that Pluto is not a planet <ref>https://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf ''International Astronomical Union'', 2005. Accessed February 9, 2022</ref>
= 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/m<sup>3</sup>, 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.
== Orbital characteristics ==
== Orbital characteristics ==
Pluto lies in a highly eccentric (nearly 25 percent) orbit around the sun. In fact, its [[apsis|perihelion]] lies inside the [[semi-major axis]] of the orbit of [[Neptune]].<ref>http://science.jrank.org/pages/5352/Pluto.html</ref>
Pluto lies in a highly eccentric (nearly 25 percent) orbit around the sun. In fact, its [[apsis|perihelion]] lies inside the [[semi-major axis]] of the orbit of [[Neptune]].<ref>http://science.jrank.org/pages/5352/Pluto.html</ref>
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.)