• 6 hours (23%)
  
  
• 12 hours (17.9%)
  
  
• 24 hours (36.5%)
  
  
• 36 hours (22.5%)
  
  

When the Earth was first formed, the average day took only six hours to pass. That is one-quarter of the average of days now, with each day taking 24 hours in the modern era. When the Earth was first formed, it spun much more quickly on its axis. It sowed as time passed, and the addition of the moon and its gravitational pull further slowed the Earth’s spin speed. Over billions of years, it reached 24 hours per day.