light year
The term "light year" is often misunderstood as a measure of time, but it actually represents an astronomical distance based on the distance light travels in one year.
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Definition
B2Astronomy
(technical, scientific)A unit of distance equal to how far light travels in one year, about 9.46 trillion kilometers or 5.88 trillion miles.
Example
- The nearest star to Earth, Proxima Centauri, is about 4.24 light years away.
- Scientists use light years to measure the distance between galaxies.
B2Informal
(figurative, informal)A metaphor for a very long distance or a very long time.
Example
- Their technology is light years ahead of ours.
- It feels like light years since we last met.
Similar
Terms that have similar or relatively close meanings to "light year":
sidereal yearspeed of lightlight conegalactic yearlight wave