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

Importance:

    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.

History:

    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.