2) There are justifications on the presence of the moon. Perhaps, collision-ejection theory of the moon gives an explains on the issues. The theory asserts that the moon exists due to the formation of debris ejected from the earth, especially when objects crushed. Collision-ejection theory claims that the newly formed earth collided with mars at an angle, which splashed the layers of the earth surface into the orbit around it. This implies that the Earth crust and mantle formed the moon though condensation. There are various facts on the moon that the theory is consistent with. Some of the facts are that the rock vaporized through the impact could have undergone depletion of volatile elements and water (Taylor 56). This leaves the moon as compared to the Earth relatively low in water.
In addition, before planetesimal struck, the material had sunk deeper into the earth, which justifies the fact that the moon contains iron-rich matter. The moon was probably formed by the lighter rock and materials that were splashed form the Earth (Moché 45). Another fact is that, the debris splashed would orbit near the ecliptic plane during the collision as long as the impacting planetesimal was near the plane. The theory is crucial since it gives a justification on the existence of the moon, as well as the tilting of the earth.
4) The most fundamental unit of measuring solar time is probably the day. The solar day is believed to be longer that the sidereal day; this can be proved through an experiment. Based on the Celestial Meridian, sidereal day refers to the time between successive crossings by a reference star. Basically, solar time is always used as a measure of time. In fact, the measurement is used in watches and clocks. In terms of hours, it is worth noting that one solar day has 24 solar hours, while one sidereal day has 23 hours and 56 minutes (Gopi 7).
The experiment is carried out in order to ascertain the difference in the solar day and sidereal day. The main aim of the experiment is to determine the length of sidereal day in solar hours. This is done by measuring the difference in time that a star takes to be a specific spot in different nights. It is worth noting that the experiment can be undertaken at any time in the course of the year.
Procedure
- An hour after the sunset, select a bright star that is well placed in the sky
- Identify an object o be a reference point of the selected star so as to measure time that the star reached the position
- Measure the exact time that the star disappeared in the reference point. Repeat this foe many nights
- Confirm that the time used is well calibrated and exact. With internet this is very possible.
- The selected star will always follow the same path, and the observation is that it appears in the point of reference earlier each night.
- Then note the difference of four minutes per day on sidereal day to solar day
- The observation relates to the 360 degrees of the earth in the orbit. For the earth o move one degree it uses four minutes. In a year, the earth has 365 days, and the earth is 360 degrees; this implies that the earth must travel the extra one degree before the sun crosses the same Meridian in the other position (Gopi 10).
Conclusively, for every four years there is a leap year so as to accommodate the sidereal days of 366.26 in the calendar.
8) The process of plate tectonics is very crucial in astronomy and the understanding of energy flow. As a matter of fact, the tectonic plates are always driven by unseen and definite forces in the earth surface. The tectonic plates do not wander or drift randomly about the surface of the earth. The outward energy flow derives the plate tectonics from the core of the earth. The process of radioactivity generates a lot of heat from various elements that decay and release a lot of energy. It is worth noting that the core of the earth is hot based on its initial formation. The reaction taking place produces a lot heat, which is then moved to the earth surface through a process called convection. The rising and falling of materials during convection process leads to a horizontal movement of the earth surface. This occurs below the crust; the part where the crust is weak gives room for fluids to rise and break the crust. The process pushes the plates, which in turn slide along the direction of the convectional currents (Kent C. Condie
3). The rate at which the heat is lost in the earth surface is very crucial in the tectonic activity of the planet. The larger bodies for example lose heat at a very slow rate, which makes them active for a long time. This is very applicable in the process of tectonic plates. In the process of convection, the giant plates within the crust ride along with the convection loops. In general perspective, the outward flow of energy in the interior part o the earth drives the plate tectonics through a convectional process. The essence behind this is that the interior of the earth is in a continuous and constant motion though convectional process. The convection in this case is a solid mantle that drives many plate tectonic processes, which include movements and formation of the oceanic crust and the continents.
9) The planets formed today and planet orbiting a first generation star would be different. It is worth noting that the difference would arise due to its contents. The planets orbiting a first generation star could probably be made up of only helium and hydrogen. On the other hand, the planets forming today would contain the elements made in the big bang, as well as the elements made in the star (Decker & Holde 159). Probably, it is evident faced on the requirement of human existence that humans would not have existed. Humans are living organisms which require oxygen, carbon, as well as elements of silicon and iron in order to build the planet that they are required to live in. In the early world, humans would not have existed because these components were not present. The earlier planet contained helium and hydrogen, which could not have supported life.
Work Cited
Condie, Kent C, and Kent C. Condie. Plate Tectonics and Crustal Evolution. Oxford: Butterworth Heinemann, 1997. Internet resource.
Decker, Heinz, and Holde K. E. Van. Oxygen and the Evolution of Life. Berlin: Springer, 2011. Internet resource.
Gopi, Satheesh. Global Positioning System: Principles and Applications. New Delhi: Tata McGraw-Hill Pub. Co, 2005. Print.
Moché, Dinah L. Astronomy: A Self-Teaching Guide. Hoboken, N.J: John Wiley, 2009. Internet resource.
Taylor, Stuart R. Solar System Evolution: A New Perspective : an Inquiry into the Chemical Composition, Origin and Evolution of the Solar System. New York: Cambridge University Press, 2001. Print.
