Why is light-year a distance?
Show answer & explanation
Answer: Distance light travels in a year
Distance light travels in a year ✓ — Correct! Light-year is a distance unit for cosmic scales. Light travels ~300,000 km/s. In one year: 9.46 trillion km (5.88 trillion miles)! Nearest star (Proxima Centauri) is 4.24 light-years away—light takes 4.24 years to reach us. Andromeda galaxy: 2.5 million light-years. We see distant objects as they were in the past—looking back in time!
Measurement of star brightness — Wrong. Brightness is measured in magnitudes. Light-year measures distance—how far light travels in one year through space.
Time for light to reach Earth — Wrong. Light-year can describe travel time, but it's primarily a distance measurement—9.46 trillion kilometers.
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