light hour
- noun
- Specialized
- The closest star system is about four light hours away, making it a challenging target for exploration.
- light hours away
Examples
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I'm about 13.5 light hours from Earth, or 14,570,000,000 km.
Blog text (1) -
The spacecraft is currently positioned almost two light hours from Earth, traveling towards Mars.
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It takes light about one light hour to travel the distance of just over 1 billion kilometers in space.
How Far
- Specialized
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Surface Forms
Morphology
The meaning is directly and compositionally derivable from 'light' (electromagnetic radiation) + 'hour' (a 60-minute period): it denotes the distance light travels in one hour. This follows regular English measurement-compound patterns (compare 'light-year', 'light-minute'), so a B1 learner who knows the constituents can infer the meaning.
Etymology
Light hour comes from a simple image: light moving for one hour. Imagine a very fast car driving without stopping for 60 minutes — the distance it covers is a light hour, so the term means 'the distance' light travels in one hour.