Earth and Mars have conjunctions every 15/7 of a year, or every 26 month or every 2 years. And it varies substantially from conjunction to conjunction because of orbital precessions and eccentricities. Is there an astronomical term for the period between two conjunctions? Like the word "olympiad" which refers to the four year period between the games.


That is called the synodic period.

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  • $\begingroup$ How does one phrase it in terms of Earth and Mars? The conjunctions in years 2033, 2035 and 2037 are closer than average. What should I call the synodic period between the conjunctions of 2033 and 2035? $\endgroup$ – LocalFluff Aug 26 '15 at 20:17
  • $\begingroup$ "The synodic period between the Earth-Mars conjunctions of 2033 and 2035." $\endgroup$ – Mark Adler Aug 26 '15 at 20:31
  • $\begingroup$ We need to make up a convenient word for that. Something like "The olympics of 2035". $\endgroup$ – LocalFluff Aug 26 '15 at 20:42
  • $\begingroup$ @LocalFluff A synodical could work as a noun (like e.g. a sabbatical used both as an adjective or a noun). $\endgroup$ – TildalWave Aug 26 '15 at 22:52
  • $\begingroup$ @TildalWave The word "synod" might work. "The Martian synod to 2033." With the risk of being arrested if one talks like that on the street. $\endgroup$ – LocalFluff Aug 26 '15 at 23:23

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