How many mm in 1 light-year?
The answer is 9.4607304725808E+18.
We assume you are converting between millimetre and light year.
You can view more details on each measurement unit: mm or
light-year
The SI base unit for length is the metre.
1 metre is equal to 1000 mm, or 1.0570008340246E-16 light-year.
Note that rounding errors may occur, so always check the results.
Use this page to learn how to convert between millimetres and light years.
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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-year

A light year, abbreviated ly, is the distance light travels in one year: roughly 9.46 × 1012 kilometres (9.46 petametres, or about 5.88 × 1012 (nearly six trillion) miles). More specifically, a light year is defined as the distance that a photon would travel, in free space and infinitely far away from any gravitational or magnetic fields, in one Julian year (365.25 days of 86400 seconds each).

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