A friend of mine saw a video that claimed the moon appears to be at the feet of the constellation Virgo about once every 17 years with its next occurrence being in September 2017. Is there any reliable sources that back this up? What I mean by a "reliable source" is an organization that speaks with authority on these matters such as NASA. I would prefer that it is available online, however I understand if it is not. If it is, please provide a direct link to it. If it is not online, please quote verbatim what it says about it, preferably in context. Also, here is a picture of what it might mean for the moon to be at the feet of Virgo (do note that the moon might not be to scale):

Moon at Virgo's feet

  • $\begingroup$ "At the feet of Virgo" is a pretty vague concept. The moon is pretty close to the ecliptic so its going to pass by Virgo once a month (Virgo is a zodiac constellation because, be definition, it is on the ecliptic). Depending on how you define "at the feet of Virgo" the moon is in this configuration about once a month, not every seventeen years. $\endgroup$
    – zephyr
    Oct 28 '16 at 18:17
  • $\begingroup$ @zephyr I guess it would mean below virgo, so near Mu Virginis. I will add a picture of where the moon might be located when it is "at the feet of Virgo". $\endgroup$ Oct 28 '16 at 18:28
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    $\begingroup$ I think my same comment applies then, this happens about once a month, not once every 17 years. Play around in this planetarium and see for yourself. You can see the (new) moon is near Mu Virginis and "at the feet of Virgo" this upcoming Oct. 30th, 2016. Either your friend is wrong, or he meant something more specific like a more precise location or else a particular moon phase (like a full moon) in conjunction with the position. $\endgroup$
    – zephyr
    Oct 28 '16 at 18:35
  • $\begingroup$ In September, Virgo sets soon after the sun. Its stars will be lost in the twilight. The moon would only be visible as a very thin crescent. $\endgroup$
    – James K
    Oct 28 '16 at 20:50
  • $\begingroup$ Perhaps this 17 year occurrence is when the sun is lined up with virgo and the moon is near her "feet" within the month of Tishri (September/October). $\endgroup$ Nov 15 '16 at 15:10

enter image description here

I think I understand the question, but don't really have an answer.

Mu Virgo, the southernmore of Virgo's two feet, has an ecliptic latitude of 9.678 degrees, meaning it's quite far north of the ecliptic.

The moon never ventures more than about 5.15 degrees from the ecliptic, so it will never be north of Mu Virgo, or even really that close.

The closest interpretation I can give: in some months, the moon's northernmost ecliptic latitude will occur near Mu Virgo, putting it "close" to Virgo's feet.

If you run http://ssd.jpl.nasa.gov/?horizons with these settings:

enter image description here

you can get a rough idea of where the moon's ecliptic latitude is maximal for each month. Of course, you can refine these settings to get more accuracy.

In theory, you can use http://wgc.jpl.nasa.gov:8080/webgeocalc/#NewCalculation to get more exact values of when the moon is furthest north of the ecliptic, but I couldn't get this to quite work out (I didn't spend very long on it).

I don't see that the ecliptic latitude's maximal position is that much closer to Mu Virgo in September 2017, but didn't look carefully.


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