Pluto is a Planet!
Since 2006, this former 9th planet out from the sun has been demoted to Dwarf Planet Status. This website will explain why its title of “9th planet from the Sun” should be reinstated. Each link will have valuable information on Pluto. It begins with the history of the planet’s name all the way to the very reasons why Pluto should remain the 9th planet from the sun.
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A Little Summary
The header photo above was taken by the New Horizons spacecraft back in 2015. At the time, very little was known about Pluto. In 1997, astronomers from the International Astronomical Union even questioned the status of Pluto and at the time made the decision for it to remain a planet. Now, Pluto has been stripped of that title, and I think that title should be restored.
What is a Planet?
The word planet came from the Greek word, “planetes” meaning “wanderer.” From the dawn of civilization, stargazers (astrologers, as they were once called) noticed bright objects travelling along the same path in the sky as the Sun and Moon. They noticed that these objects did not twinkle like ordinary stars. It also proved logical to these early scientists that, because they are so bright, that these objects were very close to Earth. Henceforth, the Greeks gave the five wandering objects a name, “planets.”
There are five known planets that can be seen in the night sky. Mercury, the closest planet to the sun, can be seen after sunset and before sunrise. Venus, the closest planet to Earth, can be viewed as the morning or evening star depending on its position in its orbit around the sun. Further out, about one and a half times the distance our Earth is to the sun, lies the red planet, Mars. Beyond Mars lies the asteroid belt and its largest object, Ceres. Beyond the asteroid belt lies mighty Jupiter, which covers one constellation of the zodiac a year. Finally, the ringed planet Saturn, which has the largest quantity of moons to ever orbit a planet.
It should be noted that a “perturbation” is a deviation of a system, moving object, or process from its regular or normal state of path, caused by an outside influence.
On March 13th 1781, William Herschel discovered these perturbations in Saturn’s orbit and used them to predict the existence of a planet beyond it. This world, named Uranus after the Greek God of the sky, was found in the constellation of Taurus. On September 23rd, 1846, Johann Gottfried Galle noticed the very same perturbations in Uranus’s orbit. This lead to the discovery of Neptune, which was found in the constellation of Aquarius.
In the early 1900’s, an astronomer named Percival Lowell noted perturbations in Neptune’s orbit. This led to the discovery of the mysterious “Planet X.” Throughout most of his life, Lowell was determined to find this mysterious world beyond the planet that was named after the Roman God of the Sea. After checking the sky for several years, Lowell died before the discovery was made….
Above is the alignment of the naked-eye planets as of April 25, 2002.
Planetary conjunction of 2002, courtesy of Stellarium.
Pluto's History
Following Percival Lowell’s death at the age of 61 in 1916, the search for the mysterious “Planet X” continued. Astronomers at the time narrowed their search on the ecliptic, which is the path that the Sun, Moon and all of the planets travel along in the background of stars. The constellations that these objects pass through are known as the Constellations of the Zodiac.
What Percival did not know was that he did photograph a world in March and April of 1915. It wasn’t until February 18, 1930 that a young astronomer named Clyde Tombaugh discovered this mysterious world found near the star Wasat, the 9th brightest star in the constellation of Gemini.
A young English girl named Venetia Burney suggested the name of this outermost world to her grandfather. She suggested the world be named after the Roman God of the Underworld and Wealth, Pluto. To honor the name of the person that led to this discovery of this distant world, in the picture above the planetary symbol is an emergence of the person’s first two initials who predicted the existence of Pluto, Percival Lowell.
This is the exact location of Pluto on the day of its discovery (image courtesy of Stellarium):
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Plutonian Statistics
Visiting Spacecraft: New Horizons (July 14, 2015)
More Info about Pluto’s Moons
Charon
Named after the ferryman who led the dead to the underworld in mythology, Charon was discovered on June 22, 1978 by astronomer James Christy. Charon’s orbital period in Earth time is 6 days, 8 hours, and 17 minutes, and the moon is in synchronous orbit around Pluto. The moon is covered with nitrogen and methane ices, and has no atmosphere.
Image courtesy of Celestia.
Styx
Named after the river that brought souls to the underworld. Styx’s orbital period is 20 days, and the moon was discovered by the Hubble Space Telescope on July 7, 2012. Styx has no atmosphere and has a water ice surface, and orbits 26,100 miles away from Pluto.
Nix
Named after the Greek goddess of darkness and night, who was also the mother of Charon. Nix’s orbital period is 25 days, and the moon was discovered by the Hubble Space Telescope in June of 2005. Nix has no atmosphere and a reddish surface similar to that of Pluto.
Kerberos
Named after the Greek three-headed dog that guarded the underworld. Kerberos’s orbital period is 32 days, and the moon was discovered by the Hubble Space Telescope on July 22, 2011. Kerberos has no atmosphere and orbits 37,000 miles away from Pluto.
Hydra
Named after the Greek nine-headed serpent that guarded the underworld. Hydra’s orbital period is 38 days, and the moon was discovered by the Hubble Space Telescope in June of 2005. Nix has no atmosphere and orbits 40,233 miles away from Pluto.
Image courtesy of the Hubble Space Telescope
In the above image, Charon is above the horizon illuminated by a very dim star, our Sun.
Pluto and Charon are thirty-nine times further from the Sun than Earth is!
If we could picture the amount of sunlight our star shines on Pluto, it would be 250 times brighter than a full moon!
It takes five hours and twenty nine minutes for the sun’s light to reach the outermost planet in our Solar System!
Recent findings about the surface temperature of Pluto indicate that it has a running anti-greenhouse effect.This causes the planet’s heat to escape into space due to reflective nitrogen and methane.
However, Pluto’s surface temperature on its sunlit side is the coldest of any planet in the solar system.
Pluto reached its closest approach to the sun on September 5, 1989!
It will reach its farthest approach from the sun in 2113!
Pluto rotates in the opposite direction of most bodies in our solar system, as does Uranus. Therefore, the Sun rises in the west and sets in the east on Pluto.
The Pluto system orbits a point outside Pluto due to Charon’s relatively large mass. This point is called its barycenter.
Pluto’s tenuous atmosphere is expected to freeze within the next few years because its orbit is headed toward its apoapsis (farthest approach a planet is to its star).
Many astronomers believe that Pluto and its satellites were once satellites of Neptune.
Click for More Info about Pluto and Charon If we could picture the amount of sunlight our star shines on Pluto, it would be 250 times brighter than a full moon! It takes 5 hours and 45 minutes for the sun’s light to reach Pluto! Recent findings regarding the surface temperature of Pluto indicate that the planet has an anti-greenhouse effect that causes its heat to escape into space; it’s believe that this is due to reflective nitrogen and methane ices. However, the surface temperature on the sunlit side is considerably warmer than the night side of the planet Mercury! Pluto reached its closest approach to the sun on September 5, 1989! It will reach its farthest approach from the sun in 2113! Pluto and Venus are the only two planets that rotate retrograde. The barycenter, or center of mass, of the Pluto system is outside of both Pluto and Charon, meaning that Pluto orbits a point outside itself. Pluto’s meager atmosphere is expected to freeze within the next few years as it heads toward its aphelion (or farthest distance from the Sun). Many astronomers believe that Pluto and Charon once orbited Neptune. Clyde Tombaugh, pictured below, is Pluto’s discoverer.
The IAU Decision
On January 5, 2005, an object was found beyond the orbit of Pluto. It was confirmed at the time that the object, now called Eris, was larger than the 9th planet.
The International Astronomical Union had a meeting in Prague, the capital of the Czech Republic. It was there that they officially defined the word “planet” for the very first time, in August of 2006.
Here is the link to go directly to their resolution:
http://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf
IAU-defined solar system, courtesy of the IAU.
As it turns out for Eris, named after the Greek Goddess of Discord, it proved to be smaller than Pluto. This was determined by observations from Hubble.
What the public didn’t know about the resolution was that only four percent of the IAU membership attended the meeting. There are 10,871 members of the IAU and only 474 members attended!
Many astronomers, including the mission leader of the New Horizons Project Alan Stern, felt the resolution was “sloppy science.” The organization’s main conclusion was that Pluto supposedly intersects Neptune’s orbit. The IAU also proclaimed that Pluto has a 3:2 resonance with Neptune. Basically, Neptune goes around the Sun three times where Pluto goes around the Sun twice. These conclusions, even though they should have been explained more thoroughly, gave the 474 members of the IAU reason to demote the 9th planet!
Go to the “Pluto’s Place In The Solar System” section on this website and you’ll be convinced that Pluto and maybe even Eris should remain planets!
Flyby Missions
Voyager 1 is a spacecraft that flew by the giant planets in 1979 and 1981, respectively. The probe in the photo above, taken by NASA, is now the furthest man made probe ever to enter interstellar space.
Scientists from the Jet Propulsion Laboratory in Pasadena, California launched this probe in 1977. As of 2014, it has been confirmed to be almost 100 Astronomical Units (Earth – Sun distance) from the Sun. It will pass within 1.6 light years of Gliese 445, a 10th-magnitude star in the constellation of Camelopardalis, The Giraffe in forty thousand years!
The Pluto Connection
Due to the alignment of Jupiter and Saturn along with the outer gas planets Uranus and Neptune, Voyager 2 was able to pass by these worlds in just twelve years’ time. Voyager 1 had the option to go past the 9th planet. The original idea was to pass by Jupiter in 1979, then perform a flyby of Saturn in 1981 and one of Pluto in 1986. The idea of a Pluto flyby was dismissed according to the scientists at JPL in favor of a flyby of Saturn’s largest moon Titan. Due to this last minute decision for a Titan flyby, Pluto was no longer aligned from Voyager 1’s position. Voyager 2 also had an impossible option to rendezvous with Pluto by having the spacecraft go inside the core of Neptune; obviously, it wouldn’t have lived to tell the tale since Neptune has the highest wind speeds of any planet in the solar system, recorded by Voyager 2 at almost three thousand miles per hour!
Pluto's Place in the Solar System
Pluto deserves its rightful place as the 9th planet out from the sun. Given all of the information provided in the previous pages of this website, Pluto is “new territory” for astronomers to gather data regarding this mysterious world for years after the New Horizons flyby.
According to the IAU, the third definition of a planet does not apply to Pluto. The picture below, courtesy of the Celestia program, proves that Pluto follows the third definition without a doubt.
In the pic directly below, the red circle is Pluto’s orbit. The outermost blue circle is Neptune’s orbit. PLUTO DOES NOT INTERSECT NEPTUNE’S ORBIT, NOR WILL THEY EVER COLLIDE WITH EACH OTHER! All Kuiper Belt objects made of ice and rock have distances that are further apart from each other in which they have cleared the neighborhood of their orbits! It should be noted that Pluto will not make a complete orbit around the sun from the time of its discovery until 2178.
Listed below are the positions of Pluto from 2006 through 2022. Like the other eight planets in our solar system, Pluto travels along the ecliptic. Its orbital eccentricity is such that in about fifty to seventy-five years, it will travel south of the ecliptic in the Constellation of Cetus, The Whale. This is the location of the other distant object Eris. Unfortunately, Eris only wanders through a small portion of the zodiac, whereas Pluto covers mostly all of them! Mercury has an inclined orbit as well. Courtesy of The Naked Eye Planets of the Night Sky Cited: pluto-path-sgr-2006-2022.png
Therefore, above all else, Pluto orbits our sun. It supports an atmosphere at least until it reaches its farthest point from our Sun. Then, the atmosphere as some astronomers believe, will freeze until it reaches its closest approach again! This world has five moons, and the count could increase when New Horizons arrives. It is spherical and follows along the ecliptic plane of our solar system. Who knows what secrets will be revealed when the very first probe visits it? Two states, New Mexico and Illinois, in which Pluto’s discoverer resided for years, have Pluto in their by-laws as being the 9th planet.
Whatever the case, each and every planet in our Solar System is unique in every aspect. Astronomers around the world may think of it as an icy dwarf object. To myself, and to many others (and I know my opinion may change when we see this object close up in July of 2015), will remember Pluto as the 9th planet in our solar system!
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