the universe

Luminosity is the amount of light that is radiated from a star. White light is the composition of all colors. In elements, the energy discharge can be displayed as light. Just by looking at the colors that are discharged, one may precisely identify the element. In understanding the universe, the Doppler effect is one of the most important tools. The Doppler effect is a shift in frequency due to a moving source. Skipping a rock on water would be an example of this effect. The circles would be off center because the rock is a moving source. The wavelength is shorter when the rock is coming toward an individual. Also, the frequency will increase and the wave crests will shorten. When the source is moving away from an individual, the wavelength increases and the frequency decreases. This principle is identical with light.

In a rainbow, the longest wavelength is the red portion and the shortest wavelength is the violet portion. If a body is emitting light and it is approaching someone, we would say the radiation is blue shifted. A red shift, on the other hand, ocurs when the emitting object is receding, or when a spectrum is shifted to longer wavelengths. Hubble measured that the farther the distance of a galaxy is from us, the greater the red shift, which is Hubble\'s law. In fact, galaxies possibly could be receding from us as fast as the speed of light. The greater the distance of a galaxy, the greater its velocity. The universe is constantly expanding in all directions. There is a raisin cake model to explicate this, considering the raisins to be the galaxies and the cake being the space between. The raisins are uniformly distributed throughout the cake, just as the galaxies are throughout the universe. If we bake the cake, as it rises the raisins will spread farther apart from one another. The neighboring raisins, closest perhaps to the one in the center, would not move as fast as ones farther away because there is more cake between it and the center raisin to expand. Therefore, all galaxies move away from each other because one is increasing.

Fritz Zwicky mapped the sky and discovered galaxies are formed in clusters. Members of a cluster move under the influence of their own gravitational pull together. The Local Group cluster consists of thirty galaxies and it is the most prominent galaxy. Containing the Milky Way and Andromeda, this is our own cluster, which is 8.5 million light years long, holds thousands of galaxies and is very dense. They all move togethr with their mutual gravities. The Virgo cluster is 52 million light years away from the Local Group. The Local Super cluster contains 100 member cluster, including the Local Group and the Virgo cluster. It is 100 million light years across and 10 million light years thick. There are three types of evolutions of galaxies, which are spiral, irregular, and elliptical. Spiral galaxies are categorized depending on how tightly bound the arms are. Irregular shaped galaxies are thought to have occurred from galactic collision. Elliptical galaxies are circular in shape to very elongated. Nebula are composed of various kinds of gas and dust, and we can tell what they are composed of by their color. A Supernova, which is an explosion of stars, leaves Nebula. Our complex molecules originated from within stars. Galaxies are not classified by shape, but rather by radio emmisions. Two of the most powerful galaxies found by telescope after World War II were M87 or Virgo A (radio name) and NGC-5128 or Centaurus A ( radio name). After time, galaxies stop emitting and their lobes spread out. Our galaxy has an active center, but we can not see it because of the spiral arms. These galaxies are in a category named BL Lac objects. Stuff shoots out of these galaxies because of the bulging galactic center. Violent radio jets are emitted that originate from a tiny central object. Galaxies are thought to form around huge black holes that are pulling matter into it at all times. Every galaxy that the Hubble space telescope has seen has a black hole in the center, so black holes could be how galaxies originate. Old Faithful is a black hole that is