Light year: Difference between revisions

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imported>Thorsten Alteholz
imported>Thorsten Alteholz
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* 1 [[parsec]] = 3.2616 ly
* 1 [[parsec]] = 3.2616 ly
* 1 [[astronomical unit| AU]] = 15.8×10<sup>-6 </sup> ly
* 1 [[astronomical unit| AU]] = 15.8×10<sup>-6</sup> ly
* 1 ly = 9.460730409 * 10<sup>12</sup> [[km]]
* 1 ly = 9,460,730,409,465.6 [[km]]    = 9.460730409 * 10<sup>12</sup> [[km]]
* 1 ly = 5.8786253 * 10<sup>15</sup> [[mi]]
* 1 ly = 5,879,882,168,716.967 [[mi]]  = 5.8798822 * 10<sup>15</sup> [[mi]]
* 1 ly = 31.039141 * 10<sup>15</sup> [[ft]]
* 1 ly = 31,039,141,763,338.582 [[ft]] = 31.039142 * 10<sup>15</sup> [[ft]]
* 1 ly = 10.346380 * 10<sup>15</sup> [[yd]]
* 1 ly = 10,346,380,587,779.527 [[yd]] = 10.346381 * 10<sup>15</sup> [[yd]]


===Distances in Light-Years===
===Distances in Light-Years===

Revision as of 12:03, 6 October 2007

The light year (symbol: ly) is the distance that the light travels in vacuum in one year. Although one might think that one year is defined as the time for the Earth to complete one revolution of its orbit of the Sun, there are still several definitions depending on the frame of reference. According to the recommendations of the International Astronomical Union (IAU), the Julian year, which has a length of 365.25 days or 31,557,600 seconds, shall be used.

The light year is a unit of distance larger than an astronomical unit (AU). It is commonly used to measure interstellar distances, where other units of measure are too small. It is rarely used in interplanetary distances, because it is too large to be useful.

Similar units are the light second, light minute, light hour, light day, light week, light month. As opposed to the light year, whose value more or less depends on the definition of year, the values of all these units are defined exactly.

numerical value

Comparison to other Units

  • 1 parsec = 3.2616 ly
  • 1 AU = 15.8×10-6 ly
  • 1 ly = 9,460,730,409,465.6 km = 9.460730409 * 1012 km
  • 1 ly = 5,879,882,168,716.967 mi = 5.8798822 * 1015 mi
  • 1 ly = 31,039,141,763,338.582 ft = 31.039142 * 1015 ft
  • 1 ly = 10,346,380,587,779.527 yd = 10.346381 * 1015 yd

Distances in Light-Years