Earth Science Essay

Stars are one of the celestial bodies found in the solar system. Such celestial object produces heat, light, and different forms of radiations such as x-rays and ultraviolet rays caused by its cosmic energy engines. All stars are made up of gas, plasma, and matters comprised of subatomic particles that are extremely heated. From the earth, it may appear that stars are near because of their radiance shining over. However, stars are very far away that most of the scientists have to develop methods in order to calculate their distance. Two of the most notable methods are the parallax technique and the use of Cepheid variable (National Geographic, 2008). The parallax technique is used in order to identify the distance of the stars that are closest to the earth. Due to the revolution of the earth to the sun, the stars that are near to the earth shifts position against the stars that are in farther positions. These changes in the position of the nearby stars are known as the parallax shift. The parallax method functions by observing the distance of the shifting process and determining the earth’s orbit diameter. From there, astronomers are able to determine the parallax angle of the star’s distance. The main principle behind the method is that â€Å"the smaller the parallax shift, the farther away the star is from the earth† (Windows to the Universe Team, 2000, n. p. ). Such method is only applicable for stars that are within the range of few hundred light years from earth. Thus, when stars exceed the given range, the parallax shift could be too small to be measured through this technique (Windows to the Universe Team, 2000). For the countless distant stars that are in the range beyond 100 light years and are in clusters found in a different galaxy, the measurement is identified through the star’s property known as Cepheid variable. Stars that have this property undergo a fixed cycle where they get brighter and dimmer. This property is common among stars that are in â€Å"old age† (Berger, 2002, n. p. ). Because of their abundance in space, astronomers measure their distance by determining the number of cycle when stars are bright (Berger, 2002). There are many ways to measure the distance of the stars. It may be obtained from the stars spectral properties, temperature, brightness, and luminosity. Because of the major efforts in improving the measurements of the distances of the stars, various ways are also formulated in order to determine the cosmic distance of other celestial bodies present in the sky. References Berger, W. H. (2002). Measuring distance to the stars. In Intro to Astronomy: Discussion of the Field of Astronomy, University of California, San Diego. Retrieved September 17, 2008 from http://earthguide. ucsd. edu/virtualmuseum/ita/06_3. shtml. National Geographic. (2008). Stars. Retrieved September 17, 2008 from http://science. nationalgeographic. com/science/space/universe/stars-article. html Windows to the Universe Team. (2000, September). How do astronomers measure the distance to stars? Is it accurate? University Corporation For Atmospheric Research. Retrieved September 17, 2008 from http://www. windows. ucar. edu/tour/link=/kids_space/star_dist. html.