Venus Synodic Period: Why 72 Degrees Away?

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SUMMARY

The Venus synodic period is defined by a cycle of 584 days, resulting in Venus appearing 72 degrees away from its previous position at maximum elongation. This phenomenon occurs because the cycle is 146 days shorter than a two-year period (730 days), leading to a fractional displacement calculated as 146/730 of a full 360-degree circle, equating to 72 degrees. This cycle is historically significant, known as the Sothis cycle in ancient Egypt and recognized by the Maya, with a complete return to the same point in the sky every 8 years, accounting for two leap days.

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  • Understanding of celestial mechanics and planetary motion
  • Familiarity with the concept of synodic periods
  • Basic knowledge of angular measurement in degrees
  • Awareness of historical astronomical cycles, such as the Sothis cycle
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  • Research the mathematical calculations behind synodic periods in astronomy
  • Explore the significance of the Sothis cycle in ancient Egyptian astronomy
  • Learn about the historical observations of Venus by the Maya civilization
  • Investigate the relationship between synodic periods and lunar cycles
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darkar
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The passage below is quotted from wikipedia:

"The cycle between one maximum elongation and the next lasts 584 days. After these 584 days Venus is visible in a position 72 degrees away from the previous one. Since 5 * 584 = 2920, which is equivalent to 8 * 365 Venus returns to the same point in the sky every 8 years (minus two leap days). This was known as the Sothis cycle in ancient Egypt, and was familiar to the Maya as well. Another association is with the Moon, because 2920 days equal almost exactly 99 lunations (29.5 * 99 = 2920.5)."

My question is why it will be 72 degrees away?
 
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:rolleyes:
darkar said:
The passage below is quotted from wikipedia:

"The cycle between one maximum elongation and the next lasts 584 days. After these 584 days Venus is visible in a position 72 degrees away from the previous one. Since 5 * 584 = 2920, which is equivalent to 8 * 365 Venus returns to the same point in the sky every 8 years (minus two leap days). This was known as the Sothis cycle in ancient Egypt, and was familiar to the Maya as well. Another association is with the Moon, because 2920 days equal almost exactly 99 lunations (29.5 * 99 = 2920.5)."

My question is why it will be 72 degrees away?


If the max. elongation cycle would coincide every two years then every 730 days it would occur at the same point in the sky.
Since the actual cycle of 584 days is 146 days short of the full cycle, then it is fractionally short by 146/730 ths of the full 360* circle.
(I think :rolleyes: )
146da./730da. X 360 degrees of a full circle = 72 *

Creator:biggrin:
 
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