Difference between revisions of "Light year"
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| − | The distance light travels in one year | + | The distance light travels in one year in a vacuum. |
| + | It is a measure of distance used in popular science to for distances to great to express in kilometers or miles. | ||
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| + | Professional astronomers prefer to use the [[parsec]] (approximately 3.26 light years) instead of the light year. | ||
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| + | The light year is easily derived from the speed of light which is 300,000,000 meters per second or <B><math>3x10^8</math></B>m/s. | ||
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| + | A light year can then be calculated to be <math>3.00x10^8</math>m/s times 3600s times 24 times 365 = <B><math>9.46x10^12</math></B> kilometers, or <B><math>5.9x10^12</math></B> miles (5900 billion miles). | ||
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| + | The distance in light years is equal to the time a light wave needs to cover that distance. | ||
| + | For instance, the [[Andromeda galaxy]] is 2.5 million light years from earth, meaning that light we see from this galaxy has been traveling for over two and a half million years.<ref>[http://www.solstation.com/x-objects/andromeda.htm]</ref> | ||
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| + | <ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref> | ||
==References== | ==References== | ||
<references/> | <references/> | ||
Revision as of 02:40, May 6, 2007
The distance light travels in one year in a vacuum. It is a measure of distance used in popular science to for distances to great to express in kilometers or miles.
Professional astronomers prefer to use the parsec (approximately 3.26 light years) instead of the light year.
The light year is easily derived from the speed of light which is 300,000,000 meters per second or <math>3x10^8</math>m/s.
A light year can then be calculated to be <math>3.00x10^8</math>m/s times 3600s times 24 times 365 = <math>9.46x10^12</math> kilometers, or <math>5.9x10^12</math> miles (5900 billion miles).
The distance in light years is equal to the time a light wave needs to cover that distance. For instance, the Andromeda galaxy is 2.5 million light years from earth, meaning that light we see from this galaxy has been traveling for over two and a half million years.[1]