Q uasar is a very energetic and distant active

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Q uasar is a very energetic and distant active galactic nucleus. Quasars are among the most luminous objects in the universe due to their high red shift. Most visible from earth. (Question was more in depth than what is listed here) Cepheid - The Cepheid variables are the most important link to galaxian distances. The nearest of these is the Clouds of Magellan and are only about 150,000 to 200,000 light years away from the sun. By determining the absolute magnitudes of Cepheids and other observable characteristics, distances to several neighboring galaxies in which Cepheids can be observed are estimated. Rays/Spectrums: Emission Line is indicative of the emission of light (rather than the absorption), it shows up as a bright line on a spectrum. Absorption lines block particular portions of the light spectrum; they indicate a particular frequency of light has been blocked. In Earth's case, particular frequencies are blocked by substances in the atmosphere, such as ozone (which blocks UV light). Used to analyze the chemical composition of celestial bodies. Electron-positron annihilation accounts for the creation of gamma rays . When an electron and a proton collide, they are both annihilated and this can result in the production of gamma rays. Spectroscope is used to view a spectrum visually; a spectrograph is used to record spectral information Red Shift - Occurs when the frequency of a photon of light is shifted towards the red end of the electromagnetic spectrum. Wave length gets longer. Gamma Rays - have the shortest wavelength on the electromagnetic spectrum. Most gamma-rays are absorbed by the Earth's atmosphere. It wasn't until astronomers were able to put a gamma-ray telescope in space, outside of the influence of our atmosphere, that they were finally able to begin collecting data. 9
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ASTRONOMY DSST 05Mar2012 X-rays - are also mostly absorbed by Earth's atmosphere, so they need to be observed from high in the atmosphere or from satellites in space. 10
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Q uasar is a very energetic and distant active galactic...

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