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Q48 (NDA-I/2019) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Astronomy and astrophysics Answer Verified

A light year is a unit of measurement of

Result
Your answer: —  Â·  Correct: A
Explanation

A light-year is a fundamental unit of measurement used in astronomy to describe very large distances [2]. Despite containing the word 'year', it is explicitly a measure of distance and not of time [1]. It is defined as the total distance that light travels in a vacuum during one Julian year (365.25 days). Given that light travels at a velocity of approximately 300,000 km/second, one light-year equals roughly 9.46 trillion kilometers [1]. This unit is essential for measuring vast scales, such as the diameter of the Milky Way galaxy, which is between 150,000 and 200,000 light-years [2]. While other units like the parsec exist for professional astronomical calculations, the light-year remains the standard for expressing the immense gaps between stars and galaxies.

Sources

  1. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 2: The Origin and Evolution of the Earth > The Star Formation > p. 14
  2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 1: The Universe, The Big Bang Theory, Galaxies & Stellar Evolution > Our Galaxy (The Milky Way) > p. 8
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SIMILAR QUESTIONS

NDA-I · 2021 · Q36 Relevance score: 6.44

Consider the following statements about Light year: 1. Light year is a unit for measurement of very large distances. 2. Light year is a unit for measurement of very large time intervals. 3. Light year is a unit for measurement of intensity of light. Which of the statements given above is/are correct?

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Light year is a unit for measurement of

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Light year is a measure of

NDA-I · 2009 · Q51 Relevance score: 3.74

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CDS-II · 2008 · Q3 Relevance score: 0.42

Which one of the following is correct ? The mean distance from the Sun to the Earth is called a/an