Light day

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

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 (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 = 1.6094799 * 10¹⁰ mi
• 1 light day = 84,980,539,275,590.551 ft = 8.4980539¹³ ft
• 1 light day = 28,326,846,425,196.850 yd = 2.8326846 * 10¹³ yd

Distances in light days

• the maximum distance between sun and Sedna is about 133,593 million km or 5.1 light days