Which one of the following is a reason why astronomical distances are measured in light-years?
Distances among stellar bodies do not change.
Gravity of stellar bodies does not change.
Light always travels in straight line.
Speed of light is always same.
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC IAS – 2021
Astronomical distances are vast, making standard units like kilometres or miles impractical. A light-year is defined as the distance light travels in one year in a vacuum. The use of light-years as a unit of distance in astronomy is based on the fact that the speed of light in a vacuum is a constant (approximately 299,792,458 meters per second). This constant speed provides a reliable basis for measuring extremely large distances across space based on time.