It could be said that the studying the solar system is a very important issue because it is the system inside which all creatures live. For this reason, there shall be a study for the smallest planet in the solar system, which is “Pluto”. The word Pluto was derived from the Romans culture. It means the god to which humans go. Romans believed that Pluto is the god of the underworld. Pluto was discovered in 1930 during an exploration of celestial bodies.
This planet has been a source of mystery even that the giant space telescope “Hubble” was able to detect very little details about its ice surface. In fact, Pluto is very small, so the human weight will be lighter if he lived on it. If one weighs 70 kg on the Earth, his weight will be 7 kg above the planet of Pluto. Pluto is smaller than the seven moons in the solar present system. this many scientists do not consider it a planet at all. In 1999, a group of scientists considered it a comet or an asteroid. The planet is 2,390 kilometers long and 5914.18 million kilometers away from the sun while its mass is 0.03 meters compared to the mass of the Earth. The year of Pluto is 247.7 compared to the year of the Earth. Pluto’s day is equivalent to 6.4 days on the Earth. While the temperature of Pluto ranges from 239 to 155 ° C.
Dwarf Pluto Atmosphere:-
The components of the atmosphere of Pluto are methane gas and nitrogen gas. In fact, the atmosphere of Pluto is thin compared to other planets. Pluto is part of a larger belt of small bodies located beyond the orbit of Neptune, called the Kuiper Belt. This region consists of thousands of icy worlds, whose diameter is not more than one thousand kilometers. This belt is the source of comets and space objects in the solar system. Although Pluto was discovered in 1930, information is still few about this remote planet. The only planet in the solar system that has not been visited by any spacecraft until July 2015 is Pluto. It is the smallest planet in the solar system, and a diameter smaller than the diameter Earth’s moon by 108 6 km. It is the farthest planet in the solar system, although Pluto enters the orbit of Neptune path and then moving away again, making scientists believe that Pluto and its moon are just moons of the planet Neptune (Redd, 2016).
First Trip to Pluto Dwarf Planet:-
The probe New Horizons went off to be the first traveler that goes to the farthest planet in the solar system. This probe was sent from the earth in January 2006 and it was planned to reach to the planet of Pluto in July 2015. In the travel to reach Pluto, New Horizons would complete nine years and a half in the space to reach to the Pluto. Pluto is the ninth planet in the solar system and it is the smallest planet in size. Pluto circles around the sun once every 247.9 Earth’s years at a distance 5880 million km. Pluto has a diameter of 2,360 km, which is roughly two-thirds the size of Earth's moon. For several years, all the information about this planet has been derived from the data of giant telescopes and this information is relatively small. Nevertheless, in 1978, astronomers discovered a relatively large moon orbiting around Pluto in a distance of 19,600 kilometers. This moon is called Charon (Howell, 2018).
The Surface of Pluto Dwarf Planet:-
In 1988, scientists discovered that Pluto's body was thin and it consists mainly of nitrogen, little methane, and carbon monoxide. In addition, Pluto’s air pressure is less 100 thousand times than the pressure of the Earth. It is believed that Pluto’s surface freezes most of the year when it is away from the sun. In 1994, Hubble Space Telescope found that 85% of the planet's surface consists of ice, showing a colorful contrast between light areas believed to be clean ice and spaces of the dark color that is believed to be unclean ice. Pluto receives one in one thousand of the rays amount received by the Earth from the sun. Therefore, Pluto is a frozen planet, while its density is twice as the density of water. Then, it was found that Pluto has rocks larger than the giant planets in the solar system. This may have been caused by chemical reactions due to the existence of the planet under a colder temperature and a low pressure of the atmosphere. Many astronomers think that Pluto was growing rapidly to be a bigger planet.
However, the influence of the gravity of Neptune that is known as Kuiper Belt affected Pluto and stopped the formation of planets there. Kuiper Belt is a ring of materials orbiting around the Sun beyond the planet Neptune, which has millions of glacial and rocky bodies resembling Pluto. Charon's origin, which is the moon of Pluto, is resulted from the accumulation of light materials caused by a collision between Pluto and another large body of Kuiper Belt. Scientists were interested in Pluto and space objects in the Kuiper Belt because they represent the raw material from which the solar system is formed. Scientists objected to Pluto being a planet because it is small and connected to the Kuiper Belt. In additions, Pluto is a glacial dwarf that is clearly different from the rest of the planets in the solar system. Nevertheless, some scientists considered it a planet because it is attractive and has a moon while they have been calling it Planet Pluto for more than 75 years. It is a dark planet and it reveals to be a rock icy ball with an atmosphere of frozen methane and nitrogen. However, it is the highest density of giant gas planets. Pluto is away with about 40 astronomical units (the astronomical unit is the average distance between the Earth and the Sun, 150 million km). It orbits it in an orbit unlike other planetary orbits (Choi, 2017).
Charon Moon of Pluto Planet:-
Charon Moon is larger than Pluto Moon, as it spins in its surrounding on a distance 19.640 km from Pluto. The diameter of Charon is 1.212 km. It is called Charon, which is a legendary name means transmissible for dead bodies through River Acheron in the underworld. Charon has been discovered on 1978. Its size is merely half Pluto-size. They take the behavior of “a twofold planet” like earth and the mood. They are very near to each other, to the extent that their gravitational pull rises ridges “supratidal” on each other. Such ridges works as brakes, which slow both of them in their spins around their axes. They are intertwined as each of them is facing the other. Pluto spins around its axe once in 64 days ground-based. Charon takes the same period of time to complete one spin around Pluto.
It is noted that, their spin direction is reversal to the spin of other planets. Pluto is the farthest planet of the solar system from the sun. Within its orbit, sometimes it is 30 astronomical units far from the sun and some other times it is 50 astronomical units far from it. The sun looks like a shining star from above the planet surface. Due to its cold weather, it freezes when the planet moves far from the sun in its spin around it. Therefore, NASA sent the spacecraft Pluto Express on 2001, in order for scientists to study the planet before it freezes. The air pressure above Pluto surface equals 100000/1 of the air pressure on earth. Hubble Telescope took Pluto planet image and its Charon moon together on 1994. The planet was 4.4 km away from earth. The telescope discovered two space objects as clear independent plates. This enabled astronomers from measuring their diameters directly. They found the diameter of Pluto is 2.320 km, and the diameter of its moon Charon is 1.270 km. Some astronomers do not consider Pluto as a real planet, as they classify it as a small among the glacial objects that constitute Kuiper Belt, which lies behind Neptune Planet, and spread in a distance equals 30 to 50 times the distance between earth and the sun. Pluto is far away from the sun with a distance 40 astronomical unit (astronomical unit is the distance between earth and the sun and equals 150 million km).
Pluto spins around the sun in 248 earth years. Its orbit is more flattened than all other planets. Therefore, it is near from Neptune when it is in the nearest point from the sun in its orbit. In fact, Pluto is deemed the first planet in terms of distance since 1969 until March 1999. Pluto spins around itself within a period of time equals 604 days of earth days. It has only one moon called “Charon”, which is considered big in comparison with the planet itself. It seems that they are spinning around each other with one face as the case for the earth and its moon. The orbits of Pluto and its moon Charon made them alternately pass in front of each other, as they have been seen from earth between 1985 and 1990, which enabled astronomers from determining their size accurately. Charon moon is 1.200 km, which makes its size close from Pluto planet itself. Thus, scientists call them the twofold planet. Pluto in its orbit around the sun performs the spin in 247.7 earth years, through which it rotates 5.9 billion km. The orbit is not circular but oval, thus it was in some points nearest to the sun from its near to Neptune. There is no opportunity to crash because it avoids the transition of Neptune orbit.
In 2002, there are many unexpected changes occurred on the surface of Pluto, because of the occurrence of a rare cosmic phenomenon. When Pluto crossed in front of two stars, their shine is dimmed due to the passing of Pluto between them. This shows that Pluto's thin atmosphere has become more intense in the last 14 years, since the last time the phenomenon was observed. The changes that occur on Pluto will be discovered only after arrival Space probe “Pluto-Capper Express”. It will be launched in 2006 to reach to Pluto 10 years later. (Note:- The project of “Pluto Kuiper Express” was canceled because of its high costs, but it was replaced by project New Horizons that similar to it. Researchers expect Pluto’s atmosphere will completely shrink in 2015. The need for access to Pluto and the performance of various calculations and measurements before the atmosphere collapsed, made the launching and arriving of Space probe “Pluto-Capper Express” very urgent task. The space probe may reach in due course or may delay. The “New Horizons” will travel 4.8 billion kilometers toward Pluto to study the only planet that still unknown in the solar system, especially the icy region of the planet. The speed of the probe is about 58,000 km / h, the journey takes nine years and a half to reach Pluto and the glacial area where the sun does not reach, to photograph Pluto and the large moon orbiting it, then analyze the atmosphere in Pluto. The probe carries the ashes of astronomer Clyde Tombaugh, the first astronomer who discovered Pluto in 1930 (Britt, 2006).
Pluto Dwarf Planet Naming:-
Unlike the other planets, the first one who is launched the Pluto was an 11-year-old girl! After discovering the planet, the scientists wanted to name it and proposed several names such as Zeus, Lowell, and Cronax. Some of these names were strongly nominated. However, a girl called Vinnitia Bayer proposed the name eventually. She told it to her grandfather who worked at Oxford University. Her grandfather told Dr. Herbert Hall Turner of Pluto’name and proposed it to his colleges after dissection settled on Pluto. The word "Pluto" used in the Roman language on the god of the underworld, meaning "the unknown thing" and in the languages of East Asia, Chinese and Japanese, meaning "the star of the angel of death." In Hindu beliefs, Guard of Hell (Schindler, 2018).
Characteristics of Pluto Dwarf Planet:-
The mystery surrounding this planet in all respects until now, most of the information about it to date is the only speculation. However, it could be said that Pluto is the smallest one of planets. It is smaller than seven moons belonging to other planets, cannot be confirmed by its mass, Scientists recently think that the Pluto’s mass is much less than they thought. The atmosphere of Pluto is mostly composed of methane and nitrogen. The temperature of Pluto’s surface is about 234. It is also believed that methane enters the composition of ice on the surface, where color tends to red. Nevertheless, many opinions were contradicting concerning the source of methane. There are beliefs that this Color is due to the presence of carbon complex compounds on its surface and some others say it absorbs ultraviolet radiation frequently led to the emergence of this color. Scientists have noticed that Pluto's density is increasing over time, despite its distance from the sun. Scientists have been confused and predicted thermal shrinkage and death within 10 years. The biggest change on its surface when passed between dark stars in 2001 lead to blocking the light. Scientists have predicted that the planet's atmosphere will collapse and shrink by 2015, but nothing is certain until today (NASA, 2015).
Pluto and Kuiper Belt:-
Kuiper Belt consists of thousands of celestial bodies. The belt is the main source of comets and asteroids. The asteroids made up of ice and rocks. The first space object was discovered in 1992. In that time, scientists were able to detect 600 space objects. It is believed that there are 100 another space object whose biggest object diameter is 3000 km. However, the planet Pluto has a diameter of 2300 km. Therefore, scientists believe that the source of Pluto is Kuiper belt because of the similarity between its characteristics and the rest of belt’ objects. For Pluto’s deviation from Titius–Bode Law, it could be said that Titius-Bode Law is an engineering consequence demonstrates the distance difference that shall exist between each planet of the solar system planet and the earth in the astronomical units. The validity of this law is proven after discovering the asteroid belts and Uranus Planet. However, this a great deviation in the planet distance from the sun has been discovered. Such deviation affected on the level of its existence in zodiac degree. All planets swim at 9 degrees, but Pluto swims at 18 degrees, on which the asteroids swim not the planets (Amos, 2015).
Pluto’s Dismissal from Planets’ Categorization:- -
Scientists have agreed to separate Pluto from the rest of the planets completely on August 24, 2006, after they placed a new definition of planets and classified them to classic and dwarf planets, and thus Pluto joined to the group of dwarf planets, scientists explain several reasons for this decision, the most important of which are the following:-
1- Size of Pluto's planet:- Pluto's size is very small if it compares to the rest of the planets, and the size is smaller than the size of our satellite. To be part of the planet group, it must be close in size from Uranus and Neptune to its extreme distance from the sun.
2- Orbit of Pluto:- It is known that the orbits of the planets are like egg-shaped and tend to be more circular, and do not intersect with each other and moves from the right to the left depending on the movement of the sun and its attractiveness, but these conditions are completely incompatible with the planet Pluto which orbit considered elliptical, so that it intersects with the orbit of Neptune planet, as it goes from left to right opposite the direction of the rest of the planets, which some scientists to think that it was a follower of Neptune and then separated at some point.
3- Pluto Features:- The planets of the solar system are divided into two main groups, the rock group including (Mercury, Venus, Earth, and Mars) and the gaseous group including (Jupiter, Saturn, Uranus, and Neptune). As for Pluto, its main component is of ice, so it does not belong to any group of the known planets (Cain, 2012).
To sum up, Pluto is the farthest planet and the brightest celestial body in an area known as the Kuiper Belt, which consists of thousands of rocky iced bodies, including asteroids that have not evolved into planets for reasons which the astronomers still unknown it. The study of these asteroids helps to know how planets form. “New Horizons” will use Jupiter's gravity to gain high speed, which will increase the speed of the probe away from the sun by nearly four kilometers per hour, allowing it to reach the ninth planet by July 2015. Some believe Pluto is a "double planet" with it only moon which known as "Charon", it was discovered in 1978. “New Horizons” will be approaching Pluto and Charon on the same day to draw a detailed map of Pluto's surface features, composition, and climate.
Astronomers discovered that Pluto is colder than they thought or imagined, and the planet's temperature was decreased, as the result of interactions between the planet's surface of nitrogen and its thin nitrogen. As it moves away from the sun, nitrogen gas condenses on the planet's surface and freezes, and as the sun approaches, the ice rises form nitrogen gas. Charon is different because it has no atmosphere, so its temperature depends on its geological composition and the reflectivity of light. Pluto is located 30 times farther from the distance between the sun and the earth, and its temperature depends on its proximity or beyond the sun in its oval orbit. While Earth and Venus are naturally affected by global warming, their surface absorbs the energy of the sun they heat, but the opposite occurs on Pluto. Instead of absorbing the sun's energy and heating the planet, the nitrogen ice on its surface turns into gas, cooling.
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