Light-Year

**Semantic type:** Quantitative Concept

**Definition:** A unit of length that would be traversed in a period of one year by an object moving at the speed of light in a vacuum (2.99792458E8 meters per second). One light year is equal to 63239.7 astronomical units, 0.3066 parsecs, 5.88E12 miles, or 9.460528405E15 meters.

**Synonyms:** - Light Year - [ly] - [ly] - l.y. - light-year - light-year - ly