Sunlight, starlight from the nearest star, and light from the nearest galaxy all take different times to reach Earth. Which of these takes the longest?
ALight from the nearest star, taking 4.2 years
BLight from the nearest galaxy, taking 25,000 years
CSunlight, taking about 8.3 minutes
DAll three arrive after the same delay
Answer & Solution
Correct answer: B. Light from the nearest galaxy, taking 25,000 years
1. Sunlight takes about 8.3 minutes to reach Earth, since the Sun is comparatively close.
2. Light from the nearest star besides the Sun takes 4.2 years, much further away.
3. Light from the nearest galaxy, a dwarf galaxy orbiting the Milky Way, takes 25,000 years, the longest of the three.
4. The three delays are wildly different, so an option claiming they are equal ignores the huge range of distances involved.
_Source: OpenStax Physics (CC BY 4.0), Ch 15 "Light", section 15.2 The Behavior of Electromagnetic Radiation_
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