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Q68 (NDA-I/2018) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Astronomy and astrophysics Answer Verified

Light year is a unit for measurement of

Result
Your answer: —  Â·  Correct: D
Explanation

A light year is a fundamental unit of measurement used in astronomy to express very large distances. Despite the word 'year' in its name, it is a measure of distance rather than time [2]. It is defined as the distance that light travels in a vacuum in one Julian year [1]. Given that light travels at a speed of approximately 300,000 km/second, one light year equals roughly 9.46 trillion kilometers [1]. This unit is essential for measuring the vast scales of the universe, such as the distance between stars and galaxies, where standard units like kilometers or miles are impractical [2]. For instance, the Milky Way galaxy's diameter is estimated to be between 150,000 and 200,000 light years [2], and the nearest star system, Proxima Centauri, is about 4.2 light years away.

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: 5.86

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?

NDA-I · 2019 · Q48 Relevance score: 5.55

A light year is a unit of measurement of

NDA-I · 2009 · Q51 Relevance score: 3.46

One light year is equal to

NDA-II · 2017 · Q60 Relevance score: 3.44

Light year is a measure of

CDS-II · 2008 · Q3 Relevance score: -0.27

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