Light-year is a length unit used to express distance, size or travel range in practical measurement work.
The light-year — the distance light travels in vacuum in one Julian year of 365.25 days — came into use in the 19th century to express the distances to stars. It is about 9.46 trillion kilometers.
Measurement system: Metric, imperial and internationally standardized length usage. SI equivalent: 1 ly = 9.460730e+15 m.
Light-year facts
- Unit name
- Light-year
- Symbol
- ly
- Category
- Length
- Measurement system
- Metric, imperial and internationally standardized length usage
- SI equivalent
- 1 ly = 9.460730e+15 m
- Common uses
- Distance, dimensions, navigation and physical measurement
Definition of the light-year
Light-year is a length unit used to express distance, size or travel range in practical measurement work.
Measurement system and SI relationship
Metric, imperial and internationally standardized length usage
SI equivalent: 1 ly = 9.460730e+15 m
History of the light-year
The light-year — the distance light travels in vacuum in one Julian year of 365.25 days — came into use in the 19th century to express the distances to stars. It is about 9.46 trillion kilometers.
Where is the light-year used?
Distance, dimensions, navigation and physical measurement