Science and Technology
2021
Space Technology India
Which one of the following is a reason why astronomical distances are measured in light-years?
D.Speed of light is always same.
C.Light always travels in straight line.
A.Distances among stellar bodies do not change.
B.Gravity of stellar bodies does not change.
Correct Answer: Option D
Astronomical distances are measured in light-years because the speed of light is constant throughout the universe, as postulated by Einstein's theory of relativity.
Light travels at approximately 300,000 kilometers per second. A light-year is defined as the distance light travels in one Earth year.
Using standard units like miles or kilometers becomes impractical for measuring the vast distances in space. Therefore, astronomers use the distance light travels as a unit of measurement.
Hence, option (d) is the correct option.
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