The BBC News website ran the following news article about the 'snow' moon and partial lunar eclipse that occurred on 10th February, 2017 (a snow moon is a full moon that occurs during February):

Spectacular snow moon regales world

February's full moon also coincides with a partial lunar eclipse.

Now, a lunar eclipse can only occur when the Moon is 'full', i.e. on the opposite side of the Earth to the sun. So, in what sense can they be said to coincide? The Cambridge Dictionary gives the following definition for coincide:

coincide verb [ I ]

to happen at or near the same time:

  • I timed my holiday to coincide with the children's.
  • If the heavy rain had coincided with an extreme high tide, serious flooding would have resulted.

Does it make sense to say:

February's full moon also coincides with a partial lunar eclipse.

The BBC seem to think so. Would it also make sense (or more or less sense) to put it the other way around, and say:

A partial lunar eclipse also coincided with February's full moon.

Does it make any difference, especially when one event cannot occur without the other?

  • I am not sure your question is about language: Eclipse, full moon and comet to occur at the same time and light up night sky in rare event - independent.co.uk/news/science/…
    – user66974
    Commented Feb 11, 2017 at 19:41
  • @Josh I completely agree that the appearance of the comet with the lunar eclipse is a coincidence, since they are independent events. However, a lunar eclipse and a full moon do not appear to be coincidental to me. I suppose that I am asking if there is some nuance to the word or not? (tag added)
    – Mick
    Commented Feb 11, 2017 at 19:57
  • 1
    I agree with you that it seems somehow "redundant" (for lack of a better term). I also question the use of "also." I "read" the linked article looking for what else the snow moon "coincided" with (to justify the "also"), but I couldn't find anything else. Regardless, +1.
    – Papa Poule
    Commented Feb 11, 2017 at 20:15
  • 2
    They coincide because they are happening at the same time. The separate events are said to coincide. The question re the BBC fits the dictionary definition to a T. You can have a FULL moon with NO lunar eclipse. It's so straightforward. The ALSO refers back to the title: so it is a spectacular SNOW MOON AND A FULL MOON.
    – Lambie
    Commented Feb 11, 2017 at 21:08
  • 2
    I have to admit I would only use coincide to refer to uncorrelated events. I dislike the directional case where all lunar eclipses occur at a full moon, but not all full moons are associated with lunar eclipses. I would avoid using coincide here.
    – Phil Sweet
    Commented Feb 12, 2017 at 1:00

1 Answer 1


I agree with you that the sentence is a bit awkward (or "redundant", as Papa Poule aptly put it in his comment above); normally we wouldn't say that two things "coincide" unless it's conceivable that they could take place at different times. For example, I think something like this is obviously bad:

His birthday this year will coincide with his turning 21.

Your example, however, does not seem anywhere near as bad as this one. I think the difference has to do with how obvious and fundamental the redundancy is; if he's turning 21 on a given day, then that day is obviously his birthday, by definition. (In anglophone cultures, that is.) By contrast, I think most people would need a second to recall (or realize) that lunar eclipses can only happen during the full moon; that may be a true fact about the world, but it's not such a basic and well-known fact as to make it inconceivable, in people's imaginations, that an eclipse could happen at another time.

  • Thanks for the kind mention! If you don't mind me asking, what is your take on my feeling that the use of the word "ALSO" in the article seems out of place here (and might even be adding to the feeling of awkwardness/redundancy we perceive in this use of "coincide")? Another user addressed my "ALSO" issue by saying that it's referring to the title and to the fact that "it is a spectacular SNOW MOON AND [ALSO?] A FULL MOON," but this explanation seems even more redundant to me since, by definition, a Snow Moon is always a Full Moon. Anyway, +1!
    – Papa Poule
    Commented Feb 12, 2017 at 17:08
  • @PapaPoule: The headline is "Spectacular snow moon regales world" and the subhead is "February's full moon also coincides with a partial lunar eclipse", so I think we're to interpret the subhead as meaning something like "February's full moon, in addition to being a spectacular 'snow moon', also coincides with a partial lunar eclipse", or perhaps "February's full moon, in addition to regaling the world, also coincides with a partial lunar eclipse."
    – ruakh
    Commented Feb 12, 2017 at 17:29

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