Research Paper on Astronomy: Planets and the Solar System

2021-07-16 14:29:51
8 pages
2017 words
Carnegie Mellon University
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Research paper
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There is a variety of natural bodies that can be observed in the sky that include the sun, the stars, the moon, the comets, and the meteoroids (NASA Solar System Exploration, 2017). According to scientific observations, the solar system has been described as a star including all other objects that revolve around it. Most stars have their planets, and therefore, the solar systems are estimated to be about tens of billions. According to NASA, the solar systems are found in the Milky Way galaxy, and there is a possibility that one system can have more than one star. The solar system that we focus on is located in an outer space of the Milky Way galaxy, and it consists of the sun (the star) and all other bodies that orbit around it. Among the bodies that orbit the sun, they include the planets and the natural satellites that include the moon, dwarf planets (and their satellites), the asteroids, comets, and other particles (NASA Solar System Exploration, 2017). The natural bodies that we see in the sky are referred as the heavenly bodies, and they represent a small fraction of all the objects that exist in the universe. For example, the earth is one of the eight planets where we can observe some of the satellites including the stars, asteroids, and comets. Our naked eyes cannot see some of the heavenly bodies, and therefore objects such as telescope are used to observe through the sky. The reason why we do not see all the heavenly bodies is that they are very far away from the earth. The above phenomenon brings the insight that the universe is very wide although the scientists have estimated the distance using the unit of length namely the light year.

Size and Distance

The size of the solar system was found to extend far beyond the eight planets that go round the sun. Kuiper (a scientist) identified a belt that is found past Neptune's orbit (NASA Solar System Exploration, 2017). The Kuiper belt consists of icy bodies that are smaller than the dwarf planet (Pluto). Past the Kuiper belt, there is an Oort cloud that surrounds the solar system (NASA Solar System Exploration, 2017). The cloud has never been observed although its existence was estimated through mathematical models and through observations of comets that are believed to originate there. The distance of the Oort cloud was estimated to be 1.6 light years away. This cloud consists of icy fragments of spaces debris estimated to be the size of a mountain although they can be larger and they orbit the sun. The Oort cloud is the limited area where the Sun's gravitational influence takes place, and it provides a space where orbiting objects turn around and come back closer to the sun. The cloud forms a shell that is estimated to extend from 5,000 to 100,000 astronomical units (NASA Solar System Exploration, 2017). An astronomical unit (AU) is the distance between the sun and the earth which is about 150 million kilometers. The sun has a heliosphere which is the bubble resulting from the solar wind. The solar wind is a stream of electrically energized gas that blows outward from the sun. The point at which the solar wind is interrupted and slows down because of the pressure originating from interstellar gases is the termination shock, and its edge lies between 80 to hundred AU (NASA Solar System Exploration, 2017).


The solar system is believed to be formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust (NASA Solar System Exploration, 2017). The cloud then collapsed due to surrounding shockwaves and formed a solar nebula. The solar nebula was a spinning and swirling disk of material. Due to the gravitational pull, more materials from the collapsed cloud were pulled in. The pressure at the core causing hydrogen atoms to combine thus forming helium that released a lot of energy and this became the sun. Due to pressure, matter from the disc clumped together and formed larger objects where some became spheres such as planets, large moons, and dwarf planets. The asteroid belt is made up of pieces of the early solar system that failed to collect together into objects like planets. Other pieces formed the asteroids, comets, small irregular moons, and meteoroids (NASA Solar System Exploration, 2017).


The planets in our solar system have a special arrangement as well as the other bodies. Near the sun only the terrestrial planets could withstand the heat because they have rocky materials namely the Mercury, Venus, Earth, and Mars (Choi, 2017). The terrestrial planets are small and occupied with solid rocky surfaces. The other planets settled as ice, liquid, and gases and they include the gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune) (Choi, 2017). The structure and the arrangement were explored early 17th century by Galileo (Choi, 2017). Through the concepts of Galileo, scientists have learned much about the solar system and the planets by first discovering that the sun was the center of the universe and planets revolved around it. The other part of the paper will explain the distinct bodies of the solar system.


When one is in a dark place or away from intense light, one can observe thousands of stars in the sky at night. With the help of a telescope, one can also see some planets as well as their moons. The celestial bodies are very distinct from the stars. The stars are celestial bodies that produce their light and heat while the planets and the moons produce light by reflecting the light produced by stars, for instance, the sun. Stars are large balls of hydrogen and helium gases whereby the hydrogen is converted into helium thus producing energy from the reaction. The energy provides heat and light that vary in brightness depending on the size of the star (Choi, 2017).

The many stars in the universe appear in groups known as the galaxies. Due to the gravitational force, the stars are pulled together and arranged in various shapes namely the spiral, ring and elliptical. The sun is one of the stars in the spiral galaxy known as Milky Way Galaxy. During the earth revolution, some stars can be observed at distinct times of the year. A group of stars at this time of the year forms a pattern in the sky referred to as the constellation. One of the most popular constellations is the Great Bear that is observed between February and May, and it has seven brightest stars with the shape of a dipper. Other constellations include the little bear, the Orion, and the Scorpius (Choi, 2017). The constellations are used by people to mark different seasons of the year, and they are imaginary because a few stars are picked to form a pattern.

The solar system

The objects of the solar system include the sun, the planets and their moons, and other bodies belonging to the sun's family. The sun is the brightest object and about 333,000 times heavier than the earth and more than million times bigger than the earth (Choi, 2017). Due to the great mass, the sun has a gravitational force that maintains the planets, their moons, and other heavenly bodies as one family. All the objects in the solar system orbit the sun in a circular path referred to as the orbits.


Planets are the second largest heavenly bodies concerning our solar system. The planets are eight in number and based on their distance from the sun; they are Mercury, Venus, Earth, Mars, Jupiter Saturn, Uranus, and Neptune. Each planet has a rotation movement around its axis. Some of the planets are visible with our naked eyes at different positions and time of the year (Choi, 2017).

Mercury is the smallest planet concerning our solar system and has a shorter distance around the sun as compared to others. It rotates at a slower speed as compared to earth, and one in mercury is equivalent to 58 times longer than a day experience on earth. It is again not the hottest despite being closest to the sun because it doesn't trap heat from the sun. It is also visible in the morning or evening at the specific time of the year (Choi, 2017).

Venus comes second after mercury, and it is the brightest and the hottest planet as well due to its thick atmosphere that is mainly composed of carbon dioxide gas which reflects plenty of light and traps more heat. It is visible in the sky, as morning or evening star. It takes 243 days to complete a rotation (one day) than it takes to orbit the sun (Choi, 2017).

Earth is the only planet that has life because of its distance from the sun with a suitable atmosphere and water that makes life possible. The atmosphere composed of carbon dioxide used by plants and animals as well as trapping enough heat (Choi, 2017).

Mars on the hand is a planet after earth that has had the most interest regarding scientific research on if life existed on this planet. It has a red-colored soil that makes it be referred to the red planet (Choi, 2017).

Jupiter is the largest and the heaviest planet and has the largest numbers of moons as compared to the rest. It has strong winds blowing on it that provides a striped look. Jupiter is also visible to the naked eyes, and when viewed using a microscope, a huge storm can be spotted (Choi, 2017).

Saturn is the planet just after Jupiter, and prominent rings characterize it. The rings are just particles of dust including ice that revolve around it. Again, this planet has a large number of moons that revolve around it (Choi, 2017).

Uranus and Neptune are the last planets respectively concerning the distance from the sun. They are also the third and the fourth regarding size, and much is known about them because they are far away from earth and the last planets to be discovered (Choi, 2017).

The moons of the planets in our solar system orbit around them and we have more than 150 planetary moons. Ganymede is the largest moon found in Jupiter. Moons vary in size, and therefore some were discovered later. The most studied is the earth's moon because of it the brightest object during the night that shines by reflecting the light from the sun. When viewed using a telescope, it has depressions on its surface that are created by falling rocks from the space. The moon takes 27 days and eight hours for one revolution around the earth and at the same time, it completes one rotation around its axis (Choi, 2017).

Dwarf planets are also objects that orbit the sun, and an example is them is Pluto. Some scientist had considered it as a plant, but because it did not manage to pull in all objects, it was considered as a dwarf planet. Others include Ceres and Eris (Choi, 2017).

Asteroids, Meteoroids, and Comets

Asteroids are also heavenly bodies in our solar system. They are identified as small, irregular, and rocky bodies that revolve the sun. An asteroid belt is found between the orbits of Mars and Jupiter. Many scientists believe that they were pieces that failed to come together to form a planet because some have moons. They measure from few meters to kilometers in width (Choi, 2017).

Meteoroids, just like asteroids, they are also pieces of rocks left over during the formation of the solar system. They orbit the sun, and when they happen to get closer to the earth, the earth's gravitational pull them, and they fall as burnings stars due to friction as they penetrate the atmosphere. Because of burning as they fall on earth, they are referred to as the shooting stars. Some may burn completely and fail to reach the earth surface while other get to the surface as remains called meteorites (Choi, 2017).

Lastly, we have the comets which are small bodies of ice and dust that orbit the sun. Comets have a longer orbit, and they take many years to complete a revolution. Once they get closer to the sun, the absorb heat, and a burning tail is observed that is made up of glowing gases and dust particles (Choi, 2017).


Choi, C. (2017). Solar S...

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