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Episode 24: Help! The Sun (or Moon) Is Moving!

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Recap: A conspiratorial or just wacky claim out there is that the sun and moon are rising and setting in different spots than they "used to." Find out why both premises in that idea are wrong.

Additional Materials:


Claim: [Clip from Coast to Coast AM, October 20, 2011, Hour 2, at 34:39] (The Sun is moving and is not rising or setting where it was before.)

The problem with this kind of claim is that people are really not as observant as they think they are. I've heard people say, "I've watched the sun set from the same spot in my house every day for the last 20 years and it's only today that it's suddenly moved!" I have yet to see anyone actually back that up with evidence. Though, to be perfectly fair, if they could, then THAT would be the extraordinary event: EVERY day of the year, or at least for 6 months out of the year, the sun will rise or set in a different location on the horizon, then it will work its way back for the next 6 months.

Instead, it's much more likely that people pay passing attention to where the sun rises or sets, and happen to look several months later and see it's in a different spot.

The cause of this is Earth's axial tilt of 23.5° relative to the plane in which it orbits. It's only on the Spring and Fall Equinoxes that the sun - from everywhere on Earth - will rise due East and set due West. As you go into summer, it will rise and set closer to your closer pole, and as you go into winter, it will rise and set closer to the other pole. So in the northern hemisphere - such as the Great State of Canada with its wonderful, kind, and caring populous ruled over by a Wise and Benevolent Dear Prime Leader - the sun will rise and set north of due East and West during the mild summer, and it will rise and set south of due East and West during the frigid winters that are colder than a L-class planet or moon like Hoth.

To visualize what's going on, and I will have diagrams in the shownotes that'll hopefully make this a bit easier - you need to go to a geocentric reference frame - meaning, think of Earth as the center, and the sun goes around us, tracing a path among the fixed stars.

If you were to photograph the sun at noon EVERY DAY for a full year, it would trace out what looks like a figure-8, known as an analemma. You may be able to use that in a cross-word someday. Anyway, the MAXIMUM height of the sun in your local sky will be on the summer solstice, and the MINIMUM will be on the winter solstice. If you measure the angle of the sun relative to the due South horizon on the summer solstice, and then measure it relative to the horizon on the winter solstice, the DIFFERENCE in those angles will be 47°, or 2 times 23.5°. The half-way point will be where the sun is on either equinox, and will actually be equal to 90°-[your latitude].

If you're still with me, get yourself a cookie but hunker down 'cause there's more geometry. If I lost you but you're still listening, the take-home message at this point is that the sun is going to be at a different height in the sky at any given time during the year. The maximum and minimum locations in the sky are directly related to your latitude and the Earth's tilt relative to its path around the sun.

The next step is to take the sun's path through the sky during the day. Let's do it on the equinox - doesn't matter which one. On the equinox, Earth's spin axis is neither pointed away nor towards the sun, but more along its orbit. As Earth rotates during the day, the sun is going to rise due East, climb to 90°-[your latitude], and set due West. It will make an arc through the sky. Think of this arc as half a hoola hoop - kids these days know what hoola hoops are, right?

Anyway, on the equinox, the ends of your half-hoola hoop are fixed right at due east and west on the horizon. As you move away from the spring or fall equinox, where that arc is on any given day will move. But it's not that you're twisting the half-hoop about those fixed East/West points - it's not just a rotation, but a translation. The end points move.

Let's say you're in the southern hemisphere, in New Zealand, surrounded by kiwis, at about 40° S latitude. On the spring equinox in September, you see the sun rising due East, climbing in the sky upwards until it hits 50° altitude, and then it will sink in the sky and set due West. It made an arc through the sky and that arc is tilted. As the months progress and you move towards the summer solstice in December, the sun's arced path through the sky is going to move - not just rotate - to be further south so that it rises south of east, climbs higher in the sky, and sets south of west. As you get to the summer solstice in New Zealand, the sun is going to rise over 20° south of East, climb to 73.5° in the sky, and set over 20° south of west. Going into winter, it'll rise and set further north of due east and west, and it will not climb nearly as high in the sky.

So, to get rid of all the math and geometry, the bottom line conceptually is that the sun moves, it almost never rises and sets due east and west, and if you claim that it rises and sets at the same point every day for 20 years but then suddenly it's rising or setting at a different location, you're wrong. It will only rise and set at the same location 2x during the year, though the change from day-to-day is fairly small.

Claim: [Clip from Coast to Coast AM, September 5, 2011, Hour 2, at 18:56] (The Moon is moving and is not rising or setting where it was before.)

Perhaps predictably, people claim the same thing for the moon. The motions of the moon CLOSELY follow those of the sun, except that the moon is tilted relative to our orbit by 5.2°. That means that in addition to the 47° range due to the 23.5° tilt of Earth relative to the sun, the moon can move ±5.2° on top of that, for a total range in the sky of about 57.5° throughout the year. BUT, it will always be within 5.2° "up or down" in the sky relative to the sun's PATH though the sky.

This means that when it's close to a new moon, it will pretty much only be ±5.2° "up or down" relative to the sun. If it were directly on the sun's path, then we would get a solar eclipse. As I'm sure almost all of you know, we don't get a solar eclipse every new moon. This also means that when it's a full moon, the moon will typically be 47.5-57.5° value "up or down" relative to where the sun was that day. Due to the actual orbital mechanics, it doesn't quite see this whole range, but you get the idea.

An effect of this is that full moons during the winter are always high in the sky, while full moons during the summer are always low in the sky. So the best time to photograph full moons is during the winter ... when it's cold outside.

And, because the phases of the moon don't exactly fit into a solar year, you won't get the moon's rising and setting positions on your horizon to repeat from year-to-year, they'll all be slightly different, and the moon's position on the horizon will shift more quickly than the sun's because the 5.2° lunar inclination is an oscillation on top of the solar one with a period of a lunar month instead of a solar year.

I should mention, though, that that rule really only applies if you're not equator-ward the Tropics of Capricorn and Cancer. If you're in there, then the geometry is slightly more complicated because you start to talk about things being past overhead and I don't really want to get into that.

When all is said and done, I've heard this claim several times when listening to Coast to Coast or reading conspiracy websites. Some websites, such as, actually cite this as evidence of a pole shift, that only a shift of Earth's rotational axis could make the sun rise or set in a different location. He provides detailed methods using Google Maps and asks people across the world to trace out where the sun is setting to take this "evidence" to broader population.

When you get right down to it, though, they're just wrong. No other way to put it: This claim, that the sun or moon is not rising or setting "where it's supposed to," is simply based on a lack of understanding of the geometry of the sun-Earth-moon system.

And as I mentioned, if my verbal explanation of this lost you a bit, I'll provide a few diagrams in the shownotes.

Provide Your Comments:

Comments to date: 8. Page 1 of 1. Average Rating:

Simon S   South Yorkshire, UK

9:06am on Tuesday, March 6th, 2012 

Excellent episode. I listened to this episode while on my exercise bike, but I couldn't fully understand it until I later looked at the 3 diagrams linked to on this page and read the audio text.

It just shows that people who make extraordinary astronomical claims from anecdotes don't check their claims by careful observation. To quote Richard P. Feynman, "You must always check that you are not fooling yourself, as you are the easiest person to fool". A simple check of high/low tide prediction tables would show whether or not the moon was shifting unexpectedly, as the predicted tides wouldn't match observation.

Stuart   Boulder, CO, USA

11:52am on Monday, March 5th, 2012

Andrew -- Yes and yes. We're talking about the maximum altitude in the sky. I should probably clarify that in the next episode. Which I should probably start writing.

sawaje   xeLompxIHnXIS

4:47am on Monday, March 5th, 2012 

17 minutes agoNo, not silly. Moving the wire moved the´╗┐ moon' round the earth' but didn't rtoate the moon itself (on its own axis). Anyhoo, if you look at all the comments you'll see that Corriere put me right and I agreed that I was indeed wrong about the moon rotating on its own axis (though not on the wire). You should read all the comments before commenting yourself otherwise you could look as silly as I did! Peace out

Andrew   New York

8:10pm on Wednesday, February 29th, 2012

@Stuart, I'm still a bit confused. Is it 90░-Your Latitude+the Sun's current declination▒5.2░? And is this calculation just for the Moon's midnight altitude? Thanks for the help.

Stuart   Boulder, CO

12:32pm on Monday, February 27th, 2012

@Andrew: Yes. For example, on the winter solstice, the sun has a declination of -23.5░ which here in Boulder means that the altitude above the southern horizon at noon is 90░-[40░ latitude of Boulder]-23.5░ = 26.5░. If there were a full moon that day, then the full moon could be anywhere between 90░-[40░ latitude of Boulder]+23.5░-5.2░ = 68.3░ and 90░-[40░ latitude of Boulder]+23.5░+5.2░ = 78.7░. As it happens, the full moon on Jan. 9, 2012 was at an altitude of 68.3░ at midnight, while the one on December 10, 2011 was at an altitude of 70.8░ at midnight. This is, unless I have my own geometry slightly incorrect, which is always possible ...

joeythejoe   Texas

8:04pm on Saturday, February 25th, 2012 

Love every episode!! Qq

Andrew   New York

10:39am on Saturday, February 25th, 2012 

What do you mean by, "this also means that when it's a full moon, the moon will typically be 47.5-57.5░ value "up or down" relative to where the sun was that day." Do you mean that the difference in altitude above the horizon between the Sun and the Moon on a particular day will fall within that range?

Chris   NZ

7:41pm on Friday, February 24th, 2012 

Another fascinating episode - thanks for sharing ...

Anyway, gotta go, my house is surrounded by Kiwis and I gotta go chase them out of my yard :)

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