Is the Earth large or small? Essay

Any information concerning the size of the earth is likely to refers to this aspect its description within the context of relativity. As one of the planets in the solar system, the earth is large relative to its planetary counterparts. It is the largest and most massive of the terrestrial planets (which include Mars, Venus, and Mercury) within the solar system. In addition, the earth is also denser than the other planets within its solar system. However, compared with the non-terrestrial planets (Saturn, Jupiter, Uranus and Neptune) the earth is very small. In comparison with the sun, the earth is tiny. The mass of the earth is 5. 9736 X 1024 kg. This, compared with the mass of the sun is 1. 99 X 1030 kg, which is 332,946 times that of the earth. On the size scales within the solar system, therefore, the earth might be considered medium sized. However, since the sun is quite miniscule compared to other stars and to the physical bodies within and beyond the galaxy, the sizes of the earth on a universal scale approaches the infinitesimal. 2. What are the major differences between parallels and meridians? Parallels or latitudes differ from meridians primarily in the directions in which they run. While parallels always run east-west, meridians run north-south in a way that allows each to cut (cross) each parallel at a different angle. This is because meridians all run through the axes of the earth, and this ensures that they all converge upon the poles. The parallels or latitudes run parallel to each other, and this ensures that they never meet each other in their journeys around the earth. One effect that this difference (in parallelism) has on the two types of lines is that while parallels are always equidistant from the equator and poles at every point on its circumference, meridians change their distances from each other the closer or further away they are from the poles. Therefore, at the equator, the distance between any two given meridian will always be greater than at any other latitude on the earth. 3. Why are vertical rays of the Sun never experienced poleward on the tropic lines? The sun’s vertical rays are experienced only between 23. 5oN and 23. 5oS primarily as a result of the tilt of the earth’s axis. This tilt measures 23. 5 degrees, so as the earth revolves around the sun, its poles tilt toward or away from the sun at this angle. During the summers (which alternate between opposing parts of the year in for the northern and southern hemispheres), the poles are tilted toward the sun. However, the angle this causes the earth to make with the sun ensures that the angles of the sun-rays hitting the earth are less than the 90 degrees which would constitute a direct hit. Because of this tilt, the rays of the sun are sometimes able to shine directly on such parts of the earth that always between the latitudes that remain in the direct path of the rays after the 23. 5o tilt. The further north or south of these latitudes one goes, the less of a direct contact the earth makes with the sun’s rays. In fact, the extreme of this is that very close to the poles at certain times of the year, the sun’s light is not seen at all. 4. On which day of the year do the vertical rays of the Sun strike the farthest north of the Equator? What is the latitude? Why? The days on which the sun’s vertical rays hit the earth at the angle farthest from the equator is approximately December 22. This is known as the Winter Solstice, and describes the time when the Northern Hemisphere experiences its shortest daytime period (or longest night-time period). The latitude at which this occurs is the 23. 5oN, which represents the latitude of the Tropic of Cancer. This occurs primarily because of the earth’s axial tilt, which is about 23 degrees toward or away from the sun. At the time of the Northern Hemisphere’s Winter Solstice, the earth is tilted away from the sun, yet the sun’s direction from the earth at that time compensates for that tilt so that its rays hit at the spot farthest north that is possible at any given time. This â€Å"spot† occurs at 23o north of the equator. 5. Explain the implications of the statement, ‘No map is totally accurate. ’ According to mapping standards held by the Unites States (and likely by other countries), maps have to maintain accuracy within a given scale. For example, for scales where one (1) inch on the map represents 24,000 inches on land (or sea), the inaccuracy level of the map should not exceed 1/50th of an inch in more than 10% of the points (USGS). These standards are based upon the premise or understanding that no map can be completely accurate. However, what this means is that at minute scales on the ground or sea, it becomes impossible to locate things with a large degree of accuracy. This can be seen more clearly when it is known that 1/50th of an inch on a 1:24,000 scale represents 40 feet (USGS). Therefore, in important expeditions that require map use, a user may expect to be ignorant concerning the exact location of a designated point within at least a 40-foot radius. 6. A globe can portray Earths surface more accurately than a map, but globes are rarely used. Why? Globes are more accurate than maps because, while the map distorts the latitude lines, the shapes of its landmasses and other features, these are kept in true to form on globes. However, globes are rarely used because of their three-dimensional natures that make them more difficult to navigate than two-dimensional maps. The shapes made by the intersection of parallels and meridians are also less like simple geometrical shapes. Because of the way in which the latitude lines are portrayed on maps (as vertical and parallel, thereby creating the illusion of squares) these are usually more suited to calculations done by the lay person or navigator. These parallel latitudes represent not real latitude lines but what has been termed loxodromes (also known as rhumb lines). These rhumb lines actually represent the constant bearing of a compass and calculations using these lines make it easier for navigators to determine the direction of their courses (Rosenberg). Maps are also more intuitively like humans view the surface of the earth. From our perspective, it does not appear to be a sphere, but a large expansive area. Therefore, maps accord more to our everyday experience and are easier for humans to translate. 7. Distinguish between GPS and GIS. Provide ways in which these tools can be useful to physical geographers. The Global Positioning System or GPS is a system that facilitates the location of objects or areas on or around the earth based on a group of satellites which have been launched into the earth’s orbit at about 11,000 miles (Corvallis). This differs from a GIS, which is a Geographical Information System—a database that holds the location of a large number of locations on the earth. The difference between the two lies in that while the GPS is the system for mapping an object, the GIS is the actual object that whose position is being mapped. The GPS system is of immense importance because of the level of accuracy it provides whether on the scales required by navigators or those required for geodesic positioning (ISSA). GIS allows geographers to be able to know, map, and locate specific regions or objects on the earths surface. It also allows them to chart paths from one location to the next by accurately calculating vectors that denote the relative distances and directions between given locations. The GPS continually expands the data available by embodying the technology that allows new places to be located and pin-pointed. Works Cited Corvallis. â€Å"Introdiction to the Global Positioning System for GIS or TRAVERSE. † CMTINC. com.Corvallis, OR: Corvallis Microtechnology Incorporated. http://www. cmtinc. com/gpsbook/index. htm ISSA. â€Å"The Global Information System. † The International Strategic Studies Association. 2004. http://128. 121. 186. 47/ISSA/gis/index. htm Rosenberg, Matt. T. â€Å"Peters Map vs. Mercator Map. † About Geography. New York: New York Times Company. http://geography. about. com/library/weekly/aa030201b. htm USGS. â€Å"Map Accuracy Standards. † United States Geographical Survey. Reston: U. S. Department of the Interior. 1999. http://erg. usgs. gov/isb/pubs/factsheets/fs17199. html