Quick Read
A light-year is a unit of distance, not time, describing how far light travels in one year.
Learn More
One light-year equals 9,460,730,472,580.8 kilometres by the definitions of light speed and the Julian year.
In Depth
The value follows from the exact speed of light multiplied by 365.25 days and is useful for interstellar distances.
Scale measurement
1 ly · distance
Quick facts
- It measures distance.
- It uses light speed in vacuum.
- It is common in astronomy.
Related objects
- compared-with: Earth–Sun distance
- compared-with: Oort Cloud
- compared-with: Local Bubble