Full name: light year
Plural form: light years
Symbol: ly
Alternate spelling: lightyear
Category type: length
Scale factor: 9460730472580800
The SI base unit for length is the metre.
1 metre is equal to 1.0570008340246E-16 light years.
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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).