Enter the orbital period (years) and the eccentricity into the Calculator. The calculator will evaluate the Aphelion Distance. 

Aphelion Distance Formula

AD = SQRT(T) * (1+e)


  • AD is the Aphelion Distance (AU)
  • T is the orbital period (years)
  • e is the eccentricity

To calculate the Aphelion Distance, add one to the eccentricity, then multiply by the square root of the orbital period.

How to Calculate Aphelion Distance?

The following steps outline how to calculate the Aphelion Distance.

  1. First, determine the orbital period (years). 
  2. Next, determine the eccentricity. 
  3. Next, gather the formula from above = AD = SQRT(T) * (1+e).
  4. Finally, calculate the Aphelion Distance.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

orbital period (years) = 80

eccentricity = 12