Sweigart Report: Solstice Full Moon Edition | Vol. 3 / No. 34.1

Photo: Chris Isherwood, CC BY-SA 2.0


So, here’s the thing. It turns out that if you write “we don’t profess to have all the answers” on your website, it doesn’t mean you get a free pass when you profess to have answers that you don’t actually have. That’s the conclusion I’m drawing after seeing this image going around Facebook today.


Because that’s not true. It’s just not. Sorry “sun-gazing.com.” (I don’t know what you should expect from a place that asks the question “what colour is your soul according to your zodiac sign?” but I guess accurate scientific commentary isn’t it.)

Yes, today is the summer solstice, and yes, it’s a full moon. But, as Phil Plait so eloquently describes over at Bad Astronomy, the confluence of full moon and summer solstice is pretty much every 19 years, with a few notable caveats mostly based on what time zone you’re in and the fact that the day in which the exact moment of solstice happens isn’t always the 20th. Nineteen years is almost exactly 235 lunar phase cycles, so if it’s a full moon on February 4th one year, it’ll be on February 4th 19 years later. (That’s called the Metonic Cycle, by the way — TIL).

Take this year, for instance. The moment of solstice is 22:34 UTC (that’s the non-acronym that means Greenwich Mean Time without mentioning Greenwich, England), which means that in, say, St. Petersburg, this year the full moon and the solstice are on different days. In other time zones, it’ll be different.

But all in all, it doesn’t really matter, because it’s all wishy-washy and I bet you can’t tell a full moon from a damn-near full moon anyway.

That said, if you’re a stickler for details, then in the UK you won’t see another “same day” full moon and summer solstice until June 21, 2062, which, while indeed a while off, is still not 2094.

Also, the full moon is basically the only time the moon is up all night, so you can see the moon during the day a whole lot. Like, really really often.

Go read Bad Astronomy for more, just because Phil Plait’s the man.


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Richard Ford Burley is a human, writer, and doctoral candidate at Boston College, as well as an editor at Ledger, the first academic journal devoted to Bitcoin and other cryptocurrencies. In his spare time he writes about science, skepticism, feminism, and futurism here at This Week In Tomorrow.