Pluto. From New Horizons’ Long Range Reconnaissance Imager (LORRI). Released July 2015. A mosaic of four medium-resolution images with true color added.
|Date of discovery||February 18, 1930|
|Name of discoverer||Clyde W. Tombaugh|
|Name origin||Greco-Roman god of wealth and the underworld|
|Order from primary||10|
|Semi-major axis||39.48168677 AU|
|Titius-Bode prediction||77.2 AU|
|Sidereal year||248.09 a|
|Synodic year||366.73 da (1.004 a)|
|Avg. orbital speed||4.666 km/s|
|Inclination||17.14175° to the ecliptic|
|Sidereal day||-6.387230 da|
|Rotational speed||47.18 km/h|
|Mass||1.305 * 1022 kg (0.218% earth)|
|Mean radius||1,185 km|
|Surface gravity||0.58 m/s² (0.0591 g)|
|Escape speed||1.2 km/s|
|Surface area||17,650,000 km² (3.460% earth)|
|Minimum temperature||33 K|
|Mean temperature||44 K|
|Maximum temperature||55 K|
|Number of moons||5 or more|
134340 Pluto is a dwarf planet in the Kuiper belt. It was once classified as one of the nine major planets, but lost this status in 2006. It is smaller than all eight major planets. NASA once thought it smaller than Eris, a recently discovered dwarf planet. But that turns out not to be true. In fact, Pluto is the largest object in all the Kuiper Belt.
Its name literally means "god of wealth" and is one of the two names for one of the brothers of Zeus; the other is Hades, or "god of the underworld." (The Romans used only the name Pluto for this particular Greek god.) (To read more about the legend of Hades/Pluto the Olympian, read here.)
According to the International Astronomical Union, it no longer qualifies as a planet because it has not cleared its orbit of other objects. But the IAU decided that under circumstances at least one observer calls suspicious. (See below.)
In 2015 the U.S. spacecraft New Horizons passed through the Plutonian system. The United States thus became the first nation-state to complete a reconnaissance of the original nine named planets. 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.
- 1 Discovery
- 2 The dwarf planet controversy
- 3 Orbital characteristics
- 4 Physical characteristics
- 5 Orbital characteristics of its moons
- 6 Pluto's origin
- 7 Observation and Exploration
- 8 In popular fiction
- 9 Satellites
- 10 References
- 11 Related links
On February 18, 1930, Clyde W. Tombaugh at the Lowell Observatory surveyed the sky, looking for a planet beyond Neptune (called "Planet X"). Other astronomers had inferred such an object from calculations based on an erroneous value for Neptune's mass and its orbital patterns. Tombaugh knew nothing of the error, but found an object anyway. Tombaugh's daughter Annette proposed the name of that object: Pluto.
Even Tombaugh realized that Pluto was not large enough to be the predicted Planet X. Astronomers continued to search in vain for it, until Voyager 2 made its flyby of Neptune, and the Jet Propulsion Laboratory scientists determined from this flyby that Neptune was significantly heavier than previously supposed. Current theory predicts no more planets other than the eight now known, but still allows for many other objects, both in the classic asteroid belt and in the Kuiper Belt, essentially a second belt of asteroids and comets.
The dwarf planet controversy
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 Eros.
In 2006, the International Astronomical Union passed the following resolution:
|“|| RESOLUTION 5A
The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet"1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d)is not a satellite.
(3) All other objects3, except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".
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. 3These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies. 
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. 
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.)
Brown suspects the IAU wanted to demote Pluto, because Pluto violates, by its very existence, every conventional theory of planetary origin.
Physical characteristicsCeres. 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.)
The most remarkable, even shocking, finding on Pluto is the lake of frozen carbon monoxide in the western "lobe" of a heart-shaped region ("Tombaugh Regio," named for the discoverer).
Orbital characteristics of its moons
Pluto and Charon make a wide binary. The barycenter of the Pluto-Charon system lies above its surface, not within it. Remarkably, the eccentricity of the Pluto-Charon wide binary is nearly zero. The eccentricities of the orbits of Pluto's other known satellites (Styx, Nix, Kerberos, and Hydra) are slightly larger than zero, but are all less than one percent.
Problems for uniformitarianism
Pluto was initially supposed to have been a moon of Neptune. But with the discovery of Charon in 1978, and the subsequent discoveries of its other moons Hydra and Nix, that theory became far less plausible.
Another hypothesis has held that Pluto entered the solar system from outside, and the Sun captured it. But if such a mass dived into the solar system from outside, then it would have followed a hyperbolic path. That it did not pass back out of the solar system to complete the hyperbola begs explanation.
But the physical characteristics of Pluto, and the orbital characteristics of its satellites, present the worst problems. The chief conventional theory to explain Charon, is that an impactor struck Pluto and caused it to eject Charon. This begs two questions:
- How could Charon and Pluto settle into nearly perfect circular orbits around their common barycenter?
- Why does Pluto have a rust color and Charon doesn't?
For that matter, why do the other moons have nearly circular orbits, inclining only slightly from Pluto's equator?
The rust color alone presents a problem. Conventional theory says the rust color comes from tholins that form from solar ultraviolet light falling on an atmosphere of methane, nitrogen, and ammonia. (Conventional scientists infer the composition of the Plutonian atmosphere strictly from spectrographic data from Earth-bound telescopes. The New Horizons spacecraft (see below) carries its own spectrophotometer.)
The carbon monoxide finding presents the worst problem. Conventional scientists simply cannot explain it.
The Hydroplate Theory
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 highly eccentric orbit of the Pluto-Charon system around the sun, is typical of the orbits of the largest trans-Neptunian objects.
Brown explains the rust color this way: Pluto has iron on its surface. The sun, acting on atmospheric water vapor, dissociated this and produced oxygen. Oxygen reacts with iron to form rust. But this change had to happen far closer to the sun than even the current perihelion of Pluto.
The carbon monoxide finding excites Brown most of all. This shows, he says, that Pluto formed from Great Flood ejecta, containing uprooted trees and shrubs from the dense forests that originally covered the pre-Flood earth. The heat of the accretion of that mass started a fire. A wood fire, burning in such a confined space, typically produces carbon monoxide, not carbon dioxide. The frozen lake is the product of those early confined fires.
Observation and Exploration
On January 19, 2006, the New Horizons mission was launched. Lead investigator Alan Stern and his team collected one U.S. Customary ounce of the ashes of Clyde Tombaugh, sealed them in a canister, and installed this on the upper deck of the New Horizons probe. Alan Stern inscribed it thus:
|“||Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system's "third zone." Adelle and Muron's boy, Patricia's husband, Annette and Alden's father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906-1997).||”|
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.
New Horizons now awaits further orders to alter its course to reconnoiter any other Kuiper Belt object it might be able to reach.
In popular fiction
Science fiction author Larry Niven once speculated on an "earlier generation" race of extraterrestrial beings that controlled the galaxy until it suffered mutual annihilation in a war with a revolting slave race. As part of that scenario, a member of that "slaver race" once had to make an emergency "landing" in a crippled spacecraft that could no longer brake to a safe approach speed. He then set a course for the earth, bailed out of his ship, and left the ship's autopilot with orders to crash-land on Neptune. Instead of that happening, the ship struck a moon of Neptune hard enough to knock it out of orbit; that moon became known as Pluto.
Pluto has also been a subject of speculation involving future efforts by humanity to colonize that body, efforts often complicated by the presence of extraterrestrial "campers" or even of pathogens, usually viruses, native to Pluto.
None of that speculation can ever be tenable anymore, after the New Horizons mission.
- "IAU0602: the Final IAU Resolution on the Definition of 'Planet' Ready for Voting," International Astronomical Union, 2005. Accessed January 14, 2008.
- Hurlbut TA, "Pluto: accidental creation," Creationism Examiner, 11 July 2015.
- Mullen J, "Pluto discoverer's ashes are aboard New Horizons probe," Cable News Network. Published 14 July 2015. Retrieved 5 August 2015.
- Jenner, Lynn. "NASA - New Horizons." NASA, October 9, 2007. Accessed July 3, 2008.
- New Horizons official site, ed. Tricia Talbert/NASA. First accessed 10 July 2015.
- Hamilton, Calvin J. "Entry for 'Pluto'." Views of the Solar System, 2007. Accessed January 21, 2008.