Waxing or waning?

This is about how to differentiate the waxing moon from the waning moon in the sky. »Waxing« is known to be the lunar phase between the new moon and the full moon (meaning the time when the crescent increases in size), whereas »waning« is known to be the lunar phase between the full moon and the new moon (the time when the crescent decreases in size). In order to remember on which side the curve is, here are some neat mnemonics.

A well-known example in English for the waxing moon is to use the spelling of the lower case letter »b«, which has a curve on the right hand side and therefore signifies »beginning«. For the waning moon, the »d« is used which has its curve on the left hand side, representing »descending«.

• ☽ = »b« = beginning (waxing)
• ☾ = »d« = descending (waning)

Another mnemonic describes the order of the waxing crescent → full moon → waning crescent, uses the shape of letters too, in this case the »D« and the »C« and creates the abbreviation »DOC«:

• ☽ = »D« = waxing moon
• O = »O« = full moon
• ☾ = »C« = waning moon

These mentioned mnemonics only work in this way in the northern hemisphere of the Earth. For the southern hemisphere you have to reverse the mnemonics (so to say »to turn them topsy-turvy«), because there, the curve of the moon is just the opposite for the observer.

39 comments

  1. Jim | 6th September 2017

    If the light is on the right, it’s going to get bright… (waxing)
    If the light is on the left, it will become less… (waning)

  2. Jack Nicholson | 5th September 2017

    For waxing and waning – What letters do you use in the German language?

  3. bruh | 14th October 2015

    smoke moons every day

  4. Anonymous | 1st October 2015

    Thanks for helping

  5. Aisha | 15th May 2015

    This is very helpful because I have a test tomorrow and I don’t pay attention in class!

    • Kendall Vertes | 21st May 2015

      yesssssss me too

  6. goyard tote | 12th August 2014

    thank you for share!

  7. Anonymous Again! | 18th March 2014

    It’s also very easy to remember.

  8. Anonymous | 18th March 2014

    Very helpful blog. That is a cool trick.

  9. super go get | 14th March 2014

    the waxing that means it is massive moon

    • super go get | 14th March 2014

      you are sad why

    • super go get | 14th March 2014

      the moon waning that means shrinking

  10. super go get | 14th March 2014

    I am sad

  11. haid | 14th March 2014

    the moon

  12. laura | 12th March 2014

    thxs for helping!

  13. Elizabeth M | 15th January 2014

    In France, the letter C for “croître” (to grow) is used when the Moon is waxing, and the letter D for “décroître” (to reduce) when the Moon wanes.

  14. Anonymous | 14th January 2014

    A few weeks ago (late Dec. 2013), I observed what looked like a smile-crescent moon in The southwestern United States — so it was neither a “D” nor a “C” (but more of a shallow “U”); and I was very surprised to see the moon filling in “from the bottom up” — ? ? ? ! I wouldn’t be able to tell which it was (waxing/waning) from the mnemonics. Love your Blog, though.

  15. Anna | 22nd December 2013

    What if the moon is less full on the top? Is it waxing or waning?

    • Jörg & Pat | 23rd December 2013

      That depends on the position of the observer on Earth (southern or northern hemisphere). You have to decide if the reduction of the circle is slightly on the left side or the right side of the top. On the northern hemisphere a reduction on the top left side would mean “waxing”, on the top right side “waning”. On the southern hemisphere it is reversed.

  16. commenter | 13th December 2013

    thanks for helping me with me report

  17. Rob | 26th October 2013

    Actually, the moon phases are “reversed” in the Southern Hemisphere.

    • Jörg & Pat | 27th October 2013

      Exactly – that’s what we have described in the last paragraph. ;-)

  18. Ginny ZB | 7th September 2013

    This was very helpful. I’m wondering how many nights it takes from the beginning of waxing to the full moon; and how many nights of waning until moon is gone until it comes the next month. I LOVE every full moon; and can always see ‘the man in the moon.’
    Does the moon have a different side that shows in Europe, for example? Do they see ‘the man’ as we see him here?
    When we were in France several years ago, I didn’t see ‘him’ very clearly; so have been wondering if I was seeing another side of the moon from what I see here in USA? Thanks, Ginny

  19. Anonymous | 5th September 2013

    very useful

  20. Rotich | 24th August 2013

    this has been of great benefit to me, because I can now differentiate between waning and waxing as used in the phases of the moon.

  21. Karina | 22nd May 2013

    this helped me soo o much I’m taking a test on this tomorrow and I’m not going to fail anymore

  22. Paula | 21st May 2013

    What is the best way to let go of your negative around you during the waning of the moon

  23. Frank | 25th February 2013

    Les stroud spoke of it on one of his Norwegian mountain shows now I know I know thanks

  24. Frank | 25th February 2013

    Les stroud spoke of it in his Norwegian mountain shows now I know thanks

  25. bill | 17th February 2013

    cool thanks

  26. bob | 5th December 2012

    thnx it helped aaalllooottt

  27. Korinka | 2nd August 2012

    In Slovak we have a similar mnemonic too. Waxing moon is D as in “Dopĺňa sa” (filling in) and waning is C as in “Cúva” (backing up).

    I never knew that on the southern hemisphere it is reversed though. Thanks :)

    • Jörg & Pat | 2nd August 2012

      That is great – thank you for this interesting information!

  28. JUDE | 14th January 2012

    GREAT WAY TO REMEMBER THE DIFFERENCE BETWEEN THE WAXING & WANING OF THE MOON. VERY CLEVER. THANKS…I WILL ALWAYS REMEMBER NOW.

  29. Marlypop01 | 4th January 2012

    Thxs! Very helpful!

  30. Lucy M | 29th December 2011

    Thank you for the info.

  31. Joana | 5th December 2011

    Good to know I had been wondering about this a few days ago

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