Difficulty with Moon Phase

I’m struggling a little bit with how to properly set up a watch hand image to rotate in sync with moon phases. I used an old Armitron watch as a guide to make my first watch face in GWS. Since the watch hand image requires two full moons, I set the end value in Rotation Properties to 56 instead of 28. This seems to work to some degree, but when I manually enter the next few full moon dates and times, the image seems to lag behind, i.e. instead of a straight-up full moon, the moon is not quite in the center just yet. With each full moon test of upcoming months, it seems to get further behind each time.

I experimented with other end values, but nothing seems to work. First of all, am I correct in thinking that when I manually enter dates and times for the future, GWS will accurately show the moon phase? I do have the image set so there is a full moon on the next date (9/2/20). From the next full moon and on to others, I don’t get a full moon position.

One of the other end values I tried was 59 since the actual moon cycle is 29.5 days, not 28. However, this doesn’t seem to work either, at least based on setting dates in GWS.

Perhaps I have this all wrong. Any help will be appreciated.

Thank you,



Hi @pdm1598123003 welcome to the community, I am not an expert in lunar phases, if it can help you, you can read these guides where they talk about the subject, while you wait for an expert on this topic to help you with your problem …


@YA_Soft – Thanks for the links. I appreciate it very much.


I think I have discovered the problem–it had to do with testing. First, it appears that setting the start value at “0” and the end value at “59” are the correct settings for my case. When I was testing this, I would type in a time and then click in another field, such as “day,” without hitting the enter key first. Changes in the cells are not automatically changed when you click out of the cell-you must hit “Enter” to affect the change. Once I figured that out, and tested various end values, I was able to get full moon settings on the appropriate future dates.

I’m curious why GWS uses 28 days and not 29.5. Although the moon orbits the earth every 27. 3 days, new moon to new moon cycles are 29.5 days.


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I am happy that you have solved the problem, if you have any other questions do not hesitate to ask