UPSC Prelims 2023·GS1·science-and-technology·space

Consider the following pairs: Objects in space Description 1. Cepheids: Giant clouds of dust and gas in space 2. Nebulae: Stars which brighten and dim periodically 3. Pulsars: Neutron stars that are formed when massive stars run out of fuel and collapse How many of the above pairs are correctly matched?

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Last updated 23 May 2026, 3:31 pm IST
  1. AOnly oneCorrect
  2. BOnly two
  3. CAll three
  4. DNone

Explanation

1. Cepheids — Giant clouds of dust and gas in space: Incorrectly matched. Cepheids are pulsating variable stars that periodically brighten and dim. Their luminosity period is directly related to their absolute brightness, making them important "standard candles" for measuring cosmic distances. Giant clouds of dust and gas are actually nebulae. 2. Nebulae — Stars which brighten and dim periodically: Incorrectly matched. Nebulae are giant clouds of dust and gas in space where new stars are born. The description given here (brighten and dim periodically) actually describes Cepheids. 3. Pulsars — Rapidly spinning neutron stars that emit regular pulses of radio waves and other radiation: Correctly matched. Pulsars are indeed rapidly rotating neutron stars that emit beams of electromagnetic radiation. Only one pair (Pulsars) is correctly matched.
science-and-technology: Consider the following pairs: Objects in space Description 1. Cepheids: Giant clouds of dust and gas in space 2. Nebulae
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