››Convert millimetre to light day

 mm light-day

 Did you mean to convert megametre millimetre to light-day

How many mm in 1 light-day? The answer is 2.59020683712E+16.
We assume you are converting between millimetre and light day.
You can view more details on each measurement unit:
mm or light-day
The SI base unit for length is the metre.
1 metre is equal to 1000 mm, or 3.8606955462749E-14 light-day.
Note that rounding errors may occur, so always check the results.
Use this page to learn how to convert between millimetres and light days.
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››Definition: Millimeter

A millimetre (American spelling: millimeter, symbol mm) is one thousandth of a metre, which is the International System of Units (SI) base unit of length. The millimetre is part of a metric system. A corresponding unit of area is the square millimetre and a corresponding unit of volume is the cubic millimetre.

››Definition: Light-day

A light day (also written light-day) is a unit of length. It is defined as the distance light travels in an absolute vacuum in one day (of 86,400 seconds) or 25,902,068,371,200 metres (~26 Tm).

Note that this value is exact, since the metre is actually defined in terms of the speed of light. The light day isn't very frequently used at all since there are few astronomical objects or distances of that magnitude; the Oort cloud, for example, is thought to extend between 290 and 580 light-days out from the Sun.

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