Light day: Difference between revisions
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The '''light day''' is the distance that the [[light]] travels in [[vacuum]] in one [[day]] and so is a unit of distance. | The '''light day''' is the distance that the [[light]] travels in [[vacuum]] in one [[day]] and so is a unit of distance. | ||
Similar units are the [[light second]], [[light minute]], [[light hour]], [[light week]], [[light month]], [[light year]]. | Similar units are the [[light second]], [[light minute]], [[light hour]], [[light week]], [[light month]], [[light year]]. | ||
===numerical value=== | ===numerical value=== | ||
As opposed to the [[light year]], whose value more or less depends on the definition of [[year]], the value of the light hour is defined exactly. | As opposed to the [[light year]], whose value more or less depends on the definition of [[year]], the value of the light hour is defined exactly. | ||
* [[velocity]] of [[light]] in [[vacuum]]: | * [[velocity]] of [[light]] in [[vacuum]]: 299,792,458 m/s <ref>Review of Particle Physics | ||
[http://stacks.iop.org/JPhysG/33/1 Particle Data Group: W.-M. Yao ''et al.'', J. Phys. G 33, 1 (2006).]</ref> ([[meter]]s/[[second]]) | |||
* 1 [[day]] = 24 [[hour]] = 1440 [[minutes]] = 86400 [[seconds]] | * 1 [[day]] = 24 [[hour]] = 1440 [[minutes]] = 86400 [[seconds]] | ||
* 1 light day = 2.5902067 * 10<sup>13</sup>m | * 1 light day = 25,902,068,371,200 m = 2.5902067 * 10<sup>13</sup>m | ||
===Comparison to other Units=== | ===Comparison to other Units=== | ||
* 1 light day = 2.5902068 * 10<sup>10</sup> [[km]] | * 1 light day = 25,902,068,371.200 [[km]] = 2.5902068 * 10<sup>10</sup> [[km]] | ||
* 1 light day = 1.6094799 * 10<sup>10</sup> [[mi]] | * 1 light day = 16,094,799,105.225 [[mi]]<ref>1 mi = 1609.344 m</ref> = 1.6094799 * 10<sup>10</sup> [[mi]] | ||
* 1 light day = | * 1 light day = 84,980,539,275,590.551 [[ft]]<ref> 1 ft = 0.3048 m</ref> = 8.4980539<sup>13</sup> [[ft]] | ||
* 1 light day = 2. | * 1 light day = 28,326,846,425,196.850 [[yd]] <ref> 1 yd = 0.9144 m</ref> = 2.8326846 * 10<sup>13</sup> [[yd]] | ||
===Distances in Light days=== | |||
Unfortunately there are no distances in nature where it make sense to express them in light days. Distances in our solar system are normally expressed in [[light second]]s up to [[light hour]]s. Distances in our galaxy are normally expressed in [[light year]]s. | |||
===Notes=== | |||
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=== | ===External links=== | ||
* [http://pdg.lbl.gov Particle Data Group & WWW edition of ''Review of Particle Physics''] | |||
* [http://stacks.iop.org/JPhysG/33/1 2006 ''Review of Particle Physics'' in printed layout] | |||
[[Category:CZ Live|Light day]] | [[Category:CZ Live|Light day]] | ||
[[Category:Astronomy Workgroup|Light day]] | [[Category:Astronomy Workgroup|Light day]] | ||
Revision as of 13:10, 11 October 2007
The light day is the distance that the light travels in vacuum in one day and so is a unit of distance.
Similar units are the light second, light minute, light hour, light week, light month, light year.
numerical value
As opposed to the light year, whose value more or less depends on the definition of year, the value of the light hour is defined exactly.
- velocity of light in vacuum: 299,792,458 m/s [1] (meters/second)
- 1 day = 24 hour = 1440 minutes = 86400 seconds
- 1 light day = 25,902,068,371,200 m = 2.5902067 * 1013m
Comparison to other Units
- 1 light day = 25,902,068,371.200 km = 2.5902068 * 1010 km
- 1 light day = 16,094,799,105.225 mi[2] = 1.6094799 * 1010 mi
- 1 light day = 84,980,539,275,590.551 ft[3] = 8.498053913 ft
- 1 light day = 28,326,846,425,196.850 yd [4] = 2.8326846 * 1013 yd
Distances in Light days
Unfortunately there are no distances in nature where it make sense to express them in light days. Distances in our solar system are normally expressed in light seconds up to light hours. Distances in our galaxy are normally expressed in light years.
Notes
- ↑ Review of Particle Physics Particle Data Group: W.-M. Yao et al., J. Phys. G 33, 1 (2006).
- ↑ 1 mi = 1609.344 m
- ↑ 1 ft = 0.3048 m
- ↑ 1 yd = 0.9144 m