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Wednesday, December 27, 2017

Light Year

What is light year?

      The term "light year" most commonly used to denote the distances between stars, galaxies, and from a point to far point of the universe. In astronomy, the familiar term to express distances is "Par-sec" which is equal to 3.26 light years.

Why it is light year?

     Because, one light year distance is equal to the distance traveled by light throughout a year. i.e; speed of light x year x 1 day in hours x 1 hour in minutes x 1 minute in seconds. It can be mathematically expressed as:
Distances of Some nearest object in light year:

    In the table below, distances of some nearest object from earth measured in light year.
* Gliese 581 Red Dwarf
** It is A0620-00 the nearest black hole i.e; 3000 light years away from Earth


    The unit of distances between stars and galaxies are measured in light year. It have been in practical use since 1984.But now the modern astronomers use parsec , light years also popularly used to express distances between interstellar and intergalactic distance.

    The usage of light year came into existence when famous astronomer Friedrich Bessel in 1838 measured the distance between a star and earth was calculated. The star was called 61-Cygni.


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