The Physics Factbook
Edited by Glenn Elert -- Written by his students
An educational, Fair Use website
|Morrison, David, Sidney Wolff & Andrew Fraknoi. Exploration of the Universe, 7th ed. Philadelphia: Saunders, 1995: 7.||"Our telescopes can see many billion of them within reach of modern instruments."||many billion|
|World Book Encyclopedia. Chicago: World Book, 1997: 205.||"Studies of distant space with optical and radio telescopes indicate that there may be about 100 billion galaxies in the universe."||100 billion|
|Fisher, David. The Origin and Evolution of Our Own Particular Universe. New York: Macmillan, 1988: 60.||"It is composed of stars grouped into galaxies about a hundred billion galaxies in the universe."||100 billion|
|The Rebirth of Cosmology. New York: Knopf, 1976: 187.||"The latest estimates have ranged anywhere from ten billion to one hundred billion galaxies."||10–100 billion|
|Galaxy Estimate Up To 125 Billion. Far News. Far Shores. citation of South China Morning Post. 9 January 1999.||"The Hubble Space Telescope has found there may be 125 billion galaxies in the universe."||125 billion|
The universe is made up of many galaxies. When galaxies were first discovered they were called island universes because they looked like islands of stars in a dark sea. New galaxies are discovered every day containing large numbers of stars. My results show the number of galaxies from some sources is the same and from some it is different. The more recent sources give larger numbers. This is because of new inventions that make it easier to find galaxies. One of these is the Hubble Space Telescope which enables us to see farther out into space and locate more of the universe's galaxies. These sources are just estimates because the numbers are always changing. Another reason that we do not know the exact number of galaxies is because they range in sizes. There can be extremely large galaxies and extremely small galaxies. The smaller galaxies are harder to detect.
Topaz Murray -- 1999
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