When were the last two or three Leap Year Februaries (29 days) with no full moon?

Assuming 29.5 days between full moons, I calculated this ought to happen roughly every 236 years. Wikipedia lists several years where February had no full moon, but <none listed> were leap years. Hint: For this to happen, there must be two full moons in <both> January and March ( one or two blue moons, depending on the definition you use).

1 Answer

  • 1 decade ago
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    If you want to get fussy about it, this never happens. That's because a "nominal day" lasts 48 hours, from 12:00:01 AM in timezone GMT -12 until 11:59:59 in timezone GMT +12. So the "day" of the full moon might be considered to last that long too -- which would easily overlap one or both ends of February somewhere in the world.

    Take for example February of 1980. There was a full moon at 02:21 UT on February 1 -- a moment which was still in January for all points in the Western Hemisphere (because those places had not yet reached midnight when the instant of full moon occurred). So does that count as a full moon in February or not?

    At the other end of the month, there was another full Moon at 21:00 UT on March 1 -- which was safely in March for the entire globe. So was there a full moon in February 1980 or not? Or for just part of the globe?

    Similar situations happened in

    1828 (full Moons 01:18 UT Feb 1 & 19:06 UT March 1)

    1760 (full Moons 06:39 UT Feb 1 & 21:26 UT March 1)

    1684 (06:02 UT Feb 1, 17:06 UT March 1)

    In 1608, there was a full Moon at 23:33 UT January 31, a moment which was already in February for almost half the globe. The next full moon was March 1 at 18:36 UT.

    Other years in which this situation occurred over part of the globe were:1608, 1580, 1504, and 1428.

    Your statistical test is complicated by the fact that Earth reaches perihelion (the closest point in its orbit around the Sun) in early January, so the Sun moves fastest across the celestial sphere in December, January, and February. This means that the synodic month (time between full moons) is a bit longer during that time of the year than average -- more like 29.7 days than 29.53 .

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