Light day

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A light day is the distance that light travels in a vacuum in one day (thus a unit of distance, not time). Similarly, there are the light second, light minute, light hour, light week, light month and light year.

Numerical value[edit]

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 a 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[edit]

• 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[edit]

• The maximum distance between the Sun and Sedna^[5] is about 133,593 million km or 5.1 light days

Notes[edit]