| my account | login-logout | resources | support | catalog | home | get webcard |

Online Classroom

Post New Topic  Post A Reply
search | help desk | commons
  next oldest topic   next newest topic
» Online Classroom   » Celestial Navigation   » Public Discussion of Cel Nav   » Waxing or waning?

Author Topic: Waxing or waning?
David Burch

 - posted April 14, 2007 08:36 PM      Profile for David Burch           Edit/Delete Post 
How to tell if the moon is waxing or waning

...in the Northern Hemisphere

There is a French saying that "The moon is lying" (La lune est menteuse), which can be used to determine if the moon is waxing or waning. I have known of this for some years but never knew what it meant, nor how to apply it. Recently a student mentioned in passing that it must mean that the shape of the moon is a letter and the letter tells us what it is doing, but it tells us wrong! Well, indeed, it is as simple as that. "Croître" means "to wax" and "Décroître" means "to wane," as shown in the figure. When the moon shows us a "C" (croître, waxing) it is lying, it is not waxing but waning, and vice versa when it shows us a "D" it is not décroître but croître.
—Thanks to Capt. Jean Faubert for filling in the details on this saying, and confirming that many French-speaking navigators have indeed learned it this way.

 - ..... but don't believe me, I am lying...

Another approach...


When I explained this discovery to my teenage daughter, who I thought might be interested since she studies French, she said, "Fine, but isn't it simpler to just recall the Celtic Goddess symbol?," which she immediately sketched and explained: the waxing moon on the left represents maiden; the full moon in the middle, mother; and the waning moon on the right, crone. The symbol is unforgettable, and I had to agree with her. Thanks Britt.

Still another approach...

...pointed out by our onboard instructor and skipper Capt. Steve Morrell. A letter "b" means the moon is getting bigger, ie waxing, and a letter "d" means the moon is decreasing, ie waning—and this time, noboby is lying.



Or just work it out on your own as we do in the Emergency Navigation book. The moon moves east relative to the sun, the side lit is the side facing the sun. If the moon is getting farther from the sun it is waxing; if getting closer it is waning.

From: Starpath, Seattle, WA

 - posted May 04, 2021 08:41 AM      Profile for GregoryB           Edit/Delete Post 
I think that the easiest way to remember waxing/waning pattern is using alliteration - "Lit on Left is Last (waning)" in the northern hemisphere (opposite in southern hemisphere).
From: Great Lakes
David Burch

 - posted May 04, 2021 08:53 AM      Profile for David Burch           Edit/Delete Post 
That is a good one. Thanks. We should add that to our article.
From: Starpath, Seattle, WA

All times are Pacific  
Post New Topic  Post A Reply Close Topic    Move Topic    Delete Topic next oldest topic   next newest topic
Hop To:

Starpath School of Navigation

Copyright, 2003-2021, Starpath Corporation

Powered by Infopop Corporation