The Cosmos, Universe: Space, Stars and Galaxies is an important topic of study because it helps an individual understand the world they are living in. Who would not want to understand clearly where they are existing and how they manage to live in such a place. This topic tries to explain to individuals why the things like stars, space and galaxies exist and the different types that are there. The study of the universe, known as astronomy has helped in the invention of many applications. The study of this topic has also helped in the development of other fields like weather forecasting. Knowing how and when the weather will change revolves around the study of stars, space and galaxies. The study of the universe has also helped in the development of the cosmic watch which has the ability to display time related to the sun and planet cycles. On the other hand, it represents the world clock (Keating, 2016). This paper will discuss in details some of the elements of the universe of the earth, that is, the stars, the space and the galaxies.
The universe also known as the cosmos as defined in the American English Dictionary is the summation of every entity that is of existence including the space and time. The universe constitutes the stars, galaxies, space, planets, the moon, other planets, different forms of energy, states of matter and everything contained in space. The size of the entire universe is not known but there exist different phenomenon about when the universe evolved and the contents in it. The study of the universe and all it is entities is known as astronomy. Astronomy is divided in to different fields depending on the type of element that wants to be studied, for example, the study of the sun is known as solar astronomy.According to Sparke and Gallagher (2007), the galaxy led to the development of the stars. In their book, they talk about the major characteristics of the stars, the Milky Way and also discuss extensively about the galaxies.
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Space
Space which is usually referred to as the outer surface is the almost vacuum areas that tend to stretch and fill the whole universe. Space appears above what can be seen by the naked eye or can also be used to refer to the vacuum that exists between the different elements of the universe. Astronomers have taken a keen look at the space and have carried out numerous studies about the space especially in the United States. With the development of the space rocket, more studies continue to be carried out (Kang, n.d).
Galaxies
Sparke and Gallagher (2007) define galaxies as the specific areas where the stars that are luminous are turned to gaseous form with the help of other reactions that are nuclear in nature and the end result being chemical elements. The light clouds that are seen in the sky are galaxies and this light comes from the stars. The authors add on and say that the galaxies contain the dark matter which is indicated by the gravitational force that we experience today. The development and the past life of the galaxy is illustrated by the shape and number of stars we see currently. The major galaxy that has been studied intensely is known as the Milky Way.
The Milky Way
Human beings live on the Milky Way which is the most common galaxy. In the Milky Way, one is able to view the dust and the gas that is found between the stars. The earth is not in the center as it might seem to and is surrounded by the dark matter and gas. The distance within the galaxy is measured in Kiloparsecs, 1kp=100pc which is estimated as 3*1016km while the stellar disk, which is the most significant part in the milky way is about 15kpc and the sun 8kpc from the center. The thin disk contains 95% of the stars and other smaller stars. The thick disk contains stars that were made earlier and has a height of 1kpc. The disk stars and the disks in the Milky Way rotate at a speed of 200km per second in a circular as opposed to other stars that move in different directions.
Apart from the Milky way which is the major type of galaxy, there are many more other galaxies which include; the elliptical galaxies which are classified in order of how spherical they are (E0 is almost spherical while E7 is elongated), shell galaxy which is also part of the elliptical galaxy but here the stars are arranged in shells, spiral and barred spiral galaxy and as the name suggests, they spin like wheels, dwarf galaxy which are smaller than any other galaxies, interacting galaxy, starburst galaxy which have dust concentrates, active galaxy, blazars, seyfert galaxy, quasar, luminous infrared galaxy which have luminosity of above 1011L and hence known to be a billion times more than the sun (Belkora, 2003).
The stars
The star is a plasma sphere that is luminous and is held together by it is own gravitational forces. Luminosity or luminous can be defined as the quantity of energy a star is able to emit in one second. This amount of energy is measured in Watts per second. The brightness that is seen or observed through a telescope which is also known as flux is the amount of energy gotten in one second on one square meter or centimeter of the telescope, unit is Wm-2 or ergs-1cm-2. When brightness received from a star is equal in all directions, the luminosity can be expressed as follows: F = L/ 4 πd 2 . The distance may not be known very well but the luminosity of the sun, which is the nearest star to the earth is known and is, Lsun=3.86*1026 or 3.86*1033ergs-1. The luminosity of stars is different and each star has it is own unique luminosity. The brightest stars are a million times brighter than the sun despite being seen faintly in the sky (Sparke &Gallagher, 2007).
The sun is the nearest star to the earth and other stars appear at night and can be seen by human beings. During the night, the stars appear as small luminous objects because of the great distance that exists between them and the earth. Stars have been grouped in to asterisms and constellations by astronomers and those that are brighter named accordingly. What is usually hard to measure in a star is the radii as much they are seen as round objects from the telescope and hence an interferometer is used to measure that. The widest star that has been recorded has a radius that is about 1000 times larger than the sun while the smallest star has a radius of 0.1R(Sparke &Gallagher, 2007).
Distribution
The stars are not evenly distributed in the universe and hence they exist in small groups known as galaxies together with the gas and dust. A normal galaxy has more than one billion stars and the universe has 100 billion plus galaxies. A study carried out in 2010 indicated that there are 300sextillion stars in the universe with others existing outside the galaxies. Proxima Centauri is the second star that is nearest to the earth apart from the sun (Michael, 2006).
Stellar Spectra
A stellar spectrum is a graphical representation of the wavelength against the flux as emitted by the stars. The stars are arranged from the hottest to the coolest.
The graph shows the most common types of stars arranged on the basis of which one is hotter to the coolest of them all. The star that is hotter is most blue and as seen on the spectra; the lines have atoms that have undergone the greatest ionization. Infrared or red wavelengths are emitted by the coolest stars and hence on the graph, they appear as less ionized atoms.
The study of the universe creates a better understanding of the world we are living in. the space which is the outer area above the galaxy and the stars creates an important area of study in science and in astronomy. The galaxy, and most importantly, the Milky Way is the area where human beings live and survive. It also consists of the different stars including the sun. The sun is the nearest star to the earth. Stars come to being as a result of the gravitational force. They also exist in different groups known as galaxies. These galaxies have different shapes and move in different directions.
In conclusion, astronomy as a scientific field has brought about significant changes especially in the military world. The study of the different elements of the universe has led to technological advancement. The space rocket, which helps in the study of space, has evolved over the years in to sophisticated machinery and is being used in different countries. More research on the different elements of the universe needs to be done to ensure that human beings fully understand the world they are living in.
References
Belkora, L. (2003). Minding the Heavens: The Story of our Discovery of the Milky Way
Kang, R. (n.d). Moons, Planets, Solar System, Stars, Galaxies in our Universe. 1-27
Keating, L. (2016). The Cosmic watch App Lets Users Explore Space, Time and Their Place in the Universe.
Sparke, L.S and Gallagher, J. S. (2007). Galaxies in the Universe: An Introduction. 2nd Edition. Cambridge University Press. 1-443
Stars: Billions and Billions. Retrieved November 17, 2016 from http://science.nationalgeographic.com/science/space/universe/stars-article/
