The solar system is situated in the outer reaches of the Milky Way Galaxy. The Milky Way Galaxy is a spiral way and is made up of over two hundred billion stars. The Milky Way Galaxy has many arms which are named for the constellations seen in those directions. Examples of the spiral arms within the Milky Way galaxy include the Sagittarius arm, Centaurus arm, Perseus arm, Cygnus arm and the Orion Spur arm. Our solar system is located in a spiral arm that is called the Orion Spur. The Orion Spur is named after the constellation “Orion the hunter”. The earth, the sun and the entire solar system is within the 3500 light years arm of the Milky Way Galaxy. The earth is situated near the interior rim of the spiral arm, approximately mid way along its length.
A black hole is essentially an object of massive size and so compact such that even light cannot escape its enormous gravity. For many decades, astronomers have been arguing that giant stars that are more massive than the sun usually end their lives as catastrophic explosions. These catastrophic explosions spray matter through the interstellar space for light years. Eventually, only a dense residue of the original star remains and if this residue or remnant exceeds three solar masses, it will eventually become a black hole. One such hole is believed to exist at the centre of our galaxy. The evidence that there is a super massive black hole at the center of the galaxy emanates from the fact that there several stars have been observed to rotate a particular object in our galaxy’s centre. If an infrared telescope is pointed towards the galactic equator, the stars are observed to be behaving strangely, moving round this object. Characteristics of this rotation have been studied and an estimation of the object’s mass can therefore be estimated. However, the orbiting stars distance essentially puts a limit on the size of the object. The current theories of astronomy stipulate that the only way such a large mass can exist in such a small volume is a massive black hole. The fact that no light is seen form this object also supports this theory.
The density wave theory is the most credible or preferred explanation for the grand design spirals .A grand design spiral is a kind of the spiral galaxy with well defined and prominent spiral arms. Unlike the flocculent and multi-arm spirals which have delicate structural features, the grand design spirals are strong and prominent. The grand design spiral arms extend visibly around the galaxy through many observable radians. About 10% of spiral galaxies are categorized as grand design type spirals. Examples of these include the M51, M74 and M81.According to the density wave theory, the spiral arms are built inside the density waves which turn around or revolve around the galaxy at different velocities from the stars within the galaxy’s disk. The stars are clustered in these dense regions due to gravitational force of attraction towards the more dense material. However, their location within the spiral arm may be temporary. When these stars come near the spiral arm, they are pulled towards the heavier material by gravity and as they move through the arm, their speeds or velocities decrease and thus slowed from going out by similar gravitational force or pull. This explains why materials cluster within the dense regions. Therefore the density wave theory directly leads to the formation or creation of grand design spirals.
In astronomy a blueshift refers to a wavelength decrease (frequency increase) while a redshift is a wavelength increase (frequency decrease). A blue shift is usually caused by the relative motion of electromagnetic radiation like light towards the individual making the observation as described by the Doppler Effect where the wavelength is decreased and the color e shifts from the electromagnetic spectrum red end towards the blue end. On the other hand, a redshift happens when the light or some other form of electromagnetic radiation emitted by an object that is headed away from the observer undergoes wavelength increase and is therefore shifted towards the electromagnetic spectrum red end. The Hubble Law is used to provide a linear relationship between the distance of a galaxy and its recessional velocity. The Hubble Law can be used to find a galaxy’s distance after measuring its redshift. All the galaxies have their own motions that are relative each other due to their mutual gravitational attraction. For galaxies that are nearby, the Hubble flow is considerably small when compared to these intrinsic velocities. Because of this fact, some of the nearest galaxies to the Milky Way are actually approaching us and therefore tend to exhibit blue shifts instead of the expected red shifts. The Milky Way and the Andromeda are among the most massive members of the Local Group of Galaxies. Therefore their gravitational interaction and subsequently their eventual collision in two and a half million years is not actually a violation of the Hubble Law.
Quasar is a distant active enormous nucleus which is very energetic. Quasars are very radiant and were initially identified as being big red shift basis of electromagnetic energy, not excluding visible light and radio waves. Quasars are sources of X-rays. The nature of these heavenly objects remained controversial until the 80s when Science came in to answer some questions. Science actually reached to an agreement that quasars are dense regions in the middle of an enormous galaxy. The quasar gets its power from an accretion disc near the black hole. In order to ascertain whether a certain heavenly body is a quasar you have to get facts about the features of quasar right. It is through the observable features of this heavenly body that one can tell whether it is actually a quasar or not. All visible quasars have redshifts of (0.056-7.085).Most quasars are more than three billion light years away, something makes them appear fade. Despite the distance, the quasars are visible from the earth because they are hyper luminous. Another outstanding feature of quasar that makes it very unique is its form. It appears to have an arc-like tidal tail which extends towards lower left. If the heavenly object appears to satisfy the above mentioned properties, and then one can easily conclude that they are actually quasars.
A Doppler shift is caused by the motion of an object through space. A Doppler shift stretches light frequency because of the fact that the object that is emitting this light is receding. On the other hand, a cosmological shift occurs when this frequency of light is stretched by space expansion. Two objects are essentially receding in a Doppler shift. If these objects were for example in coordinate grid, both or one of them would be altering its coordinates as separation takes place between the two. The frequency drop is caused due to the fact that it usually takes a significantly long time for each wave crest to reach the observer who is observing the object’s receding motion. In a cosmological redshift, the objects may not necessarily be receding through space. However, the space that exists between them is in real sense expanding. If the two objects are pictured to be in a coordinate grid, then it emanates that the grid is actually the one expanding or growing. Here, the frequency drop is occasioned by the fact that light waves in the vicinity are stretching out, gaining longer wavelengths with each passing year as the space that the waves reside in stretches around them. Another primary difference between the two red shifts is that in the Doppler redshift, the objects receding cannot actually recede more rapidly than the light speed. However in a cosmological red shift, the receding objects actually recede faster than the speed of light. There is also a small difference in the Doppler vs. the Cosmological redshift, so it is possible for one to determine the kind of redshift that one is observing by making measurements of their characteristics.
Astronomers have for thousands of years been wrestling with basic questions about the age and size of the universe. Questions have been asked of whether the universe actually goes on forever or whether it has an edge somewhere. In 1929, however, an astronomer Edwin Hubble made a critical discovery that the universe is actually expanding. Scientists started to explore other aspects of the universe that might existed in the past, for example it was found that the earth was initially hotter and denser. It was also found that there were a variety of nuclear reactions that took place under the relatively higher temperatures of the universes. These reactions that sparked radiation were responsible for the forming of some of the larger elements in the universe. Later, it was discovered that there was considerably some radiation that was still left over from the early universe and this came to be known as Cosmic microwave Background Radiation. As the universe continues expending, this Cosmic microwave Background Radiation continues growing cooler. If the expansion of the universe continues, the microwave radiation will continuously be red shifted towards the radio spectrum and even further beyond since there is not actually an upper limit on light wavelength although a practical limit exists with which the light wavelengths can be detected. In regards to temperature, the microwave radiation will approach absolute zero temperature but will never actually reach it. The radiation will essentially become undetectable.
Although it has not yet been confirmed it is believed that during early times when the temperatures were very high the entire fundamental forces of nature existed as one. However as temperatures dropped, this force broke into four distinct forces that we currently have in modern Science. The super unified theories states that the strong forces separated or was formed second after the gravitational force. The electromagnetic forces followed and finally the weak forces. Therefore according to the super unified theory that explains the formation of the four fundamental forces, the strong forces were the ones which were formed secondly. Although the grand unified theory states that the strong forces were formed first, the theory is regarded as less credible since it does not include the gravitational force which is actually the force associated with the formation of the solar system. Therefore as long as the solar system was in existence; there is no way one can argue that the gravitational force was not existent. Scientists have thus branded the super unified theory as the most plausible in explaining the formation of the four fundamental forces. However Science has not been able to tell the sequence over which forces were made. All the conclusions are actually based on assumptions.
The ability of a stellar spectral type to sustain life depends on the conditions that are characteristic to the type. The common elements, gases and compounds present within a certain spectral determine whether it can actually support life or not. A spectral type that sustains life is luminous enough and has temperatures which are mild enough to sustain life and life processes. The spectral are classified from O, B, A, F, G, K to M.O is the hottest spectral and M is the coolest. The hot spectral cannot definitely support life due to the temperatures. G is luminous enough and has suitable temperature range that can support life. Although F and K have been said to support life in recent studies, the credibility of this study remains to be affirmed spectral which is illuminated by the sun is the only spectral which has been confirmed to support life. The earth falls under this spectral and this is confirmation that it actually supports life. There is a balance of gases, compounds and energy in the G spectral and this is actually what supports life and growth.
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