IAS Gyan

Daily News Analysis


1st September, 2023 Geography

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A rare astronomical phenomenon known as the "Super Blue Moon"


  • The moon's orbit around Earth is elliptical, taking 27.3 days.
  • A super moon occurs when the moon is near its perigee (closest point to Earth) during a full moon.
  • The moon's illuminated side is fully visible during a full moon, creating a bright circle in the sky.
  • Super moons also occur during new moons, but they are not visible.

Blue Moon and Its Definition

  • A "blue moon" refers to the occurrence of two full moons within a single month.
  • The lunar cycle is 29.5 days, occasionally leading to a second full moon at the end of a month occasionally.
  • NASA supports this definition, and it happens every two to three years.

August 2023 Scenario

  • The first full moon occurred on August 1, which was a super moon.
  • The second full moon, on August 30-31, will be even larger due to its proximity to perigee.

Moon's Color and Atmosphere

  • Moon appears more yellow/orange near the horizon due to longer travel through the atmosphere.
  • Shorter, bluer wavelengths are scattered, leaving longer, redder wavelengths.
  • Dust or pollution can intensify the moon's reddish hue.

Size and Brightness of Super Moon

  • A super moon (at perigee) is about 14% larger and 30% brighter than a "micro moon" (at apogee).
  • The difference in size may not be noticeable to most people.
  • Brightness could be more discernible, influenced by factors like the "Moon illusion," cloud cover, and pollution.


Q) Which of the following statements is true about super blue moons?

A) A moon that appears blue in color due to atmospheric conditions.

B) A term used to describe a moon that is exceptionally large and bright.

C) The occurrence of two full moons within a single month.

D) A rare alignment of a full moon with Earth's perigee.

Answer: C