Talk:2172: Lunar Cycles

Explain xkcd: It's 'cause you're dumb.
Revision as of 17:15, 6 July 2019 by Hawthorn (talk | contribs) (Phase x distance and supermoons)
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Is it possible that the size of the Earth and the moon are supposed to be comparisons of how big the Earth looks from the moon vs. how big the moon looks from the Earth? 172.69.170.88 (talk) (please sign your comments with ~~~~)

Why would that have a cycle different from the distance cycle?Barmar (talk) 20:20, 5 July 2019 (UTC)

Where is the total eclipse of the heart? Actually, why do we not have a total eclipse of the hart - when all deer are hidden?

A very quick and dirty (probably flawed, until I can plug things into a suitable visualiser to check and/or improve my initial idea) attempt to describe the nature of the square/circle oscilations of the Moon might well be smething like |r.cos(θ)−r.sin(θ)|.|sin(t/λ)| + |r.cos(θ)+r.sin(θ)|.|sin(t/λ)| + |r.√(2/π)|.|cos(t/λ)|=k ...only then you'd also want to make k a quantity also multiplied by the relative Earth/Moon size cycle. Either way, YMoonMV. 141.101.98.88 00:41, 6 July 2019 (UTC)

Isn't the square/circle a reference to rounded corner rectangles. If you increase the corner radius of a square, enough, you get a circle. SDSpivey (talk) 05:37, 6 July 2019 (UTC)

Does anyone know of a real chart similar to the format of the last panel? That might be a cool thing to link to. 162.158.75.166 16:38, 6 July 2019 (UTC)

Astrology

I think this is primarily an astrology joke. Astrologers often use astronomical cycles (both real and made up) to "predict" future events or explain historic events. By having enough cycles, they can usually come up with results like "skinny jeans are always popular whenever the happy moon is in Pices and wet Mars is in the same Chinese zodiac as Mercury".

There's also possibly an allusion to Fourier transforms.

Phase x distance and supermoons

I've been absolutely nerd-sniped by the "Phase x distance" in the bottom diagram. As far as I can figure out, if you multiply phase and distance, you should end up with a new cycle with a period of (29.5 x 27.5) = 811.25 days, which is about 2 years. A supermoon is when a full moon occurs when the Moon is closest to the Earth, so this phase x distance figure is effectively a supermoon detector - that's why supermoons occur at the peaks in Randall's diagram.

But when I looked into supermoons a bit - specifically this diagram from Wikipedia - other sources shows supermoons occurring on a yearly cycle - we supposedly get them every year. How can that be the case, if the two lunar cycles only synchronize every 2 years? It seems to me like there has to be at least one out of every two years where we get no supermoons at all - ie. the full moon is always coinciding with the moon being furthest away.

I feel like I must have made a mistake or wrong assumption, but I can't figure out what it is. Hawthorn (talk) 17:15, 6 July 2019 (UTC)