The Space Exploration SE question When our Moon is hiding Mars, is it possible to create a radio communication between Earth and Mars? links to this short article in the popular press Mars is hiding behind the Moon this morning with the sub-headline

It’s a twice-a-year occultation; like the eclipse, but it’s Mars, and there’s no shadow

As answer(s) to the question mention, the Moon is smaller than Earth so an occultation would not be visible everywhere on Earth, so let's just consider it an occultation if it happens anywhere on Earth.

Question: Does a lunar occultation of Mars happen twice a year? Is the Moon's diameter big enough and it's orbit's inclination with respect to the ecliptic small enough that it can pass between Mars and some place on Earth twice a year?


2 Answers 2


Does a lunar occultation of Mars happen twice a year?

No, in the sense that the number of lunar occultations of Mars per year is quite variable and not always two.

I do not have a reference handy, but I am sure that there are some years with no occultations.

And we can see that in other years the number can be both less than and much greater than two:

  • 1
    $\begingroup$ Well this seems quite conclusive, thanks! I've edited a bit to make it clearer (to me at least) but feel free to edit further or roll back. $\endgroup$
    – uhoh
    Commented Dec 22, 2020 at 5:02

Moon-Mars Occultations occur every 174 to 188 Days

Average worldwide interval (based on 500 years) between occultations is 180 days. In a calendar year, zero to five occultations can occur. Annual occultation doesn't occur on average about once in 15 years. (Source)

Moon will occult Mars 3 times in 2021. Here is the map


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