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How fast does light travel through empty space?
AAbout 300,000 kilometers per second
BAbout 300,000 kilometers per hour
CAbout 30,000 kilometers per second
DAbout 3,000 kilometers per second
Answer & Solution
Correct answer: A. About 300,000 kilometers per second
1. Light covers a fixed distance in each second of travel.
2. That distance is about 300,000 kilometers, so the speed is 300,000 kilometers per second.
3. Even at this speed light needs more than 4 years to reach us from the nearest star.
_Source: OpenStax Astronomy (CC BY 4.0), Ch 4 "Earth, Moon, and Sky" and Ch 5 "Radiation and Spectra", section 5.1 The Behavior of Light_
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