Monday, June 20, 2016

When the full moon meets the summer solstice

It's one of these days when you would want to grab your 'fellow' journalists, shake them and shout: look at the numbers, st*pid! Countless web stories tell us that today (20 June 2016) full moon and summer solstice fall on the same day and that this is super-rare and thus newsworthy. Alas a simple check of the actual times tells you that full moon was at 11:03 UTC and solstice will be at 22:34 UTC - which is already on 21 June in all of Asia and most of Europe. So much for the coinciding dates which are true mostly for the Americas but simply do not exist for the majority of humanity.

So one has to ignore absolute dates and just go after the time difference to figure out - if one so desires - whether the 11 1/2 hours time difference today is a rarity. A table full moon times and a solstice & equinox calculator allow for a quick check: In 1910 there was a 12 1/2 hour difference (June 22/20 vs. 7 UTC), in 1929 a 6 hour difference (June 22/4 vs. 21/22 UTC), in 1948 a 40 minute difference (June 21/12 UTC), in 1967 a 2 1/2 hour difference (June 22/5 vs. 3 UTC), in 1986 an 11 hour difference (June 22/4 vs. 21/16 UTC) and in 1997 a 13 hour difference (June 20/19 vs. 21/8 UTC). Oh, and there was 2005 with a 22 hour difference (June 22/4 vs. 21/6 UTC): In Chicago e.g. solstice was at 1:46 a.m. CDT and full moon at 11:15 p.m. CDT - on the same day, 21 June (though in subsequent nights).

So this year's half-day difference isn't so rare at all: We had comparably close pairs of full moons and equinoxes in 1997 and 1986 and much closer pairs in 1967 and especially 1948. It is particularly obnoxious that the 1997 case - a mere one Metonic cycle ago - is flatly ignored in the "reporting" today. The reason, though, is obvious and casts a sharp light on how media mechanisms work: since full moon was 5 hours before midnight UTC while solstice was 8 hours after midnight UTC the pair appeared on two different dates also in most of the U.S. and so wasn't "important" (and the scanty 2005 case was overlooked, too). In contrast to the current 'sensation'. Sigh ...

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