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Posted 30 Apr 2024

2 min read

  • Earth rotates on its axis relative to the Sun every 24 hours mean solar time, with an inclination of 23.45 degrees from the plane of its orbit around the Sun. 

 

  • Earth’s rotation is affected by three major geophysical processes
    • Tidal dissipation: Friction between ocean water and the sea floor — both in shallow seas and in deep-ocean — has progressively slowed Earth’s rotation. 
    • Earth’s core: Changes in the flow of currents in the molten outer core affecting its spin.
    • Glacial melt: As polar glaciers melt, the water mass gets redistributed throughout the oceans, pooling most noticeably around the equator. 
      • It changes the shape of Earth, making it flatter and slows down its rotation speed

 

  • Findings of the study: 
    • Earth’s rotation is speeding up in recent years due to changes in its core, however, melting of polar ice mass due to climate change have decelerated such speeding up
    • To keep clocks in sync with the Earth’s rotation, speeding up of Earth’s rotation would have necessitated addition of a negative leap second in two years’ time.
      • However, climate change has delayed such addition by another three years, to 2029. 

 

About Leap Second

  • Historically, Coordinated Universal Time (UTC) is followed as time standard, in which a day lasts 86,400 seconds (24 hours * 60 minutes * 60 seconds).
    • However, average length of a day depends on Earth’s rotation speed. 
  • In case of fluctuations in Earth’s rotation speed, leap seconds are added to UTC. 
    • A negative leap second is subtracted in case of slowing of Earth’s rotation while a positive leap second is added to compensate for speeding up of Earth’s rotation. 
  • Tags :
  • Climate change
  • Earth's Rotation
  • Time keeping
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