The Moon wobbles

45 Comments
Posted December 4th, 2008 in Astronomy. Tags: , , , , , .
Lunar wobbling animation

This is what you get if you take a photo of the Moon every night for a month, then make a movie out of those pictures. The Moon’s phases aren’t surprising, but the Moon also appears to grow and shrink as it orbits the Earth. This happens because the Moon’s orbit is slightly elliptical; its distance to the Earth varies by about 10%.

Also, the Moon appears to “wobble” from left to right. That’s because the Earth’s gravity pulls harder on the Moon the closer it is to the Earth, so the Moon travels faster in its orbit when it’s closer to the Earth. The Moon’s rotation rate matches its average orbital speed (which is why we only see one face of the Moon), but its orbital speed varies during the orbit while its rotation rate remains fixed, so the Moon appears to wobble from left to right.

2009-08-10 Update: I’ve noticed that many people arrive at this article by googling moon wobbles. All the other sites on the first page claim that “moon wobbles” are responsible for explosions, mass-murder, earthquakes, terrorism, etc. Sadly, I need to emphasize that the wobbling I’m describing can’t possibly result in these kinds of ludicrous effects.

Last modified February 6th, 2012
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45 Responses to “The Moon wobbles”

  1. Also, if you look carefully, you’ll notice a slight up-down wobble as well.

    The origin of this wobble is totally different: it’s caused by the fact that the Moon’s axis of rotation isn’t quite perpendicular to the line that connects the Earth and the Moon.

    In other words, the Moon wobbles up and down for the same reason that the Earth experiences seasons.

  2. Interesting, it doesn’t surprise me that the moon wobbles to a certain extent. The 10% part surprised me, larger than I would’ve thought.

  3. Chanda Walker posted on 2009-07-04 at 17:14

    Beautiful visual. I’m thrilled to see this. Thanks for sharing.

    Have you ever researched why the moon looks so much larger at certain times of the year? For example, the harvest moon seems very much larger than a typical moon. I’ve always wanted to stop and figure this out but I’ve been just simply too lazy.

    • Beautiful visual. I’m thrilled to see this. Thanks for sharing.

      I can’t claim credit for the image, it’s from here.

      Have you ever researched why the moon looks so much larger at certain times of the year? For example, the harvest moon seems very much larger than a typical moon.

      I think you’re referring to the moon illusion where the moon appears larger and closer when it’s near the horizon rather than directly overhead. That’s probably a quirk of human vision rather than an inherent property of the moon’s orbit. I say this because the moon’s angular size is actually slightly larger when it’s directly overhead than when it’s on the horizon because we’re 1 earth radius closer to the moon when it’s directly overhead.

      There are quite a few hypotheses to explain this illusion, but most of them are inadequate. Here’s a very comprehensive overview where the author argues that “oculomotor micropsia” is responsible.

  4. Nice pic. The “Moon Wobbles” you describe are not the “Moon Wobbles” that mark disaster-prone phases in the world. These other Moon Wobbles were discovered in the 1930’s, when research by astrologer Carl Payne Tobey (1902-1980), the original editor of Astrology Magazine, revealed that disasters occur in cycles associated with the conjunction (0°), opposition (180°) and square (90°) from the Sun to the Moon’s Node. These powerful contacts occur when the Sun and the Node are in the same sign, or the opposing sign, or when the Sun is in a square aspect to the nodal axis. They are especially potent when the New Moon or Full Moon are square to the Nodes.

    I gather you are skeptical of the astrological POV, since you use the word “ludicrous” but you should read my article to get a better idea of what is actually being discussed.

    Best wishes
    Rob Tillett

    • I gather you are skeptical of the astrological POV, since you use the word “ludicrous”

      I’m skeptical of astrology because it’s been repeatedly disproven. It’s certainly not a science.

      … you should read my article to get a better idea of what is actually being discussed.

      … A highly unscientific analysis that makes no astrophysical sense and doesn’t even bother to calculate a p-value?

      Unless you use rigorous statistical methods, you’ll continue to draw bizarre conclusions from random noise, just like Carl Payne Tobey did.

      • truth seeker posted on 2009-11-02 at 10:37

        I think that if you choose not to see you will not see regardlesss of what is real. Science is a religion. So it is limited but do not try and tell that to the limited visioned scientist. And just as science is finally bumping up against religion and the truth is being revealed…there will always be those who refuse to see anything beyond their limited ability. If you cannot concieve of it you cannot see it. And by the way, rigorous statistical methods only prove that the scientist affects the experiment. There is no way of getting around it, we are all connected.

      • Science is a religion.

        Only in the sense that baldness is a hair color. I’ve previously defined religion and science; they seem completely different. If your definitions differ from mine, please tell me how– explicitly— so I can understand what you’re saying.

        So it is limited but do not try and tell that to the limited visioned scientist.

        There’s no need to tell us, because we already recognize that science is limited.

        And just as science is finally bumping up against religion and the truth is being revealed…

        I’ve noted that science isn’t capable of revealing truth at all. Science is limited to developing models that make unique predictions, which can then be compared to experiment.

        And by the way, rigorous statistical methods only prove that the scientist affects the experiment.

        How ironic that you write such an anti-scientific sentence on a computer– a device that works based on principles of modern quantum mechanics. Without rigorous experimentation, the flaws of classical physics wouldn’t have been discovered, so semiconductors probably wouldn’t have been invented. If generations of scientists hadn’t poured their lives into understanding the properties of light, the fiber-optic cables that transmitted your words to this website wouldn’t exist.

        I can only assume that you didn’t bother to read any of the links I provided in my last comment. They conclusively show that astrologers can’t make predictions that are more accurate than random chance.

      • John posted on 2010-01-17 at 09:39

        The moon and other planets and sun all have a force upon our planet. If the moon can move oceans than it can also slightly move thicker magma both creating massive preasure on our delicate outer crust. Major recorded events of catastrophes coralate with lunar and solar events and that is factual. And if meteor can have such long long orbits around earth and or sun this proves the far reaching effect of gravity. The moon is so massive and so close its effects are enourmous especially when there is a solar eclipse. The gravity is magnified and more concentrated. God says the planets are for a sign and wonders, read!!!!!!!!

      • The moon and other planets and sun all have a force upon our planet.

        Yes, scientists have known about universal gravitation since the time of Newton.

        If the moon can move oceans than it can also slightly move thicker magma both creating massive pressure on our delicate outer crust.

        Yes, the moon’s gravity causes body tides where the solid earth is compressed at tidal frequencies. One reason we notice tides in the ocean is because ocean tides are ~3x larger than body tides; what we actually observe at the beach is the difference between the ocean tide in the water and the body tide of the beach itself.

        But this is well established in mainstream science, and has nothing to do with these ridiculous astrology claims.

        Major recorded events of catastrophes correlate with lunar and solar events and that is factual.

        Solar storms such as coronal mass ejections shorted out telegraph wires in 1859, shut down a Canadian power grid in 1989 and disrupted communications satellites in 1994. The near-complete lack of sun spots during 1645-1715– a period later called the Maunder Minimum— worsened a “Little Ice Age” on Earth.

        But, of course, that’s not what these astrologers are talking about. And there aren’t any lunar events that affect Earth aside from eclipses and regular variations in tide heights, all of which are accurately predicted by modern science.

        Instead of declaring your statement to be “factual” maybe you should consider providing evidence to back it up.

        And if meteor can have such long long orbits around earth and or sun this proves the far reaching effect of gravity.

        Not nearly as impressively as observations of galactic superclusters, which show that gravity reaches across billions of light years.

        Again, this is irrelevant. Physicists understand very well that gravity has infinite range, but we also know that it follows an inverse square law in the weak field approximation. One consequence is that the doctor in the delivery room can exert a larger gravitational force on a newborn baby than most planets (depending on how obese the doctor is and the exact distance to the baby).

        The moon is so massive and so close its effects are enormous especially when there is a solar eclipse.

        No, spring tides are larger whenever the moon is “new” (which means it’s dark, so it’s roughly in between the Sun and Earth.) It doesn’t have to be exactly in between the Sun and the Earth as in the case of a solar eclipse.

        For example, spring tides also occur whenever the moon is full (which means it’s entirely lit up, so it’s roughly on the other side of the Earth as the Sun.) That’s because, as I’ve discussed, high tides happen on both sides of the Earth simultaneously.

        The gravity is magnified and more concentrated.

        No. Just… no. Gravity isn’t ever magnified or concentrated. The spring tides I just discussed happen because the gravitational force vectors of the Moon and Sun add constructively, rather than partially canceling as in the case of neap tides.

        God says the planets are for a sign and wonders, read!!!!!!!!

        Maybe I should read all the rigorous, peer-reviewed sources you provided to back up these astrology claims? Oh, wait…

  5. Hunchback Jack posted on 2010-06-13 at 13:45

    Thank you for a page about the moon wobble that *doesn’t* have anything to do with astrology, earthquakes, or other pseudo scientific nonsense, but that actually explains why it appears to wobble.

    I got here via half a dozen of those other sites, and I was beginning to worry about our prospects as a species. Your page restored my confidence. :)

    HBJ

  6. TEDDY posted on 2011-03-17 at 11:43

    Have you heard of the Chaos affect? Buttlefly flaps wings.. hurricane … We are all connected in somewhere to the fabric of the universe and are one, entanglement – universe has been entangled as a single system right from the Big Bang, ergo the moon can and does have an effect on mass-murder, earthquakes, and sadly terrorism, etc. Notice Japan’s earthquake and Tsunami and riots around the world and economic collapse. No one is an island here. Gravity is one of the 4 fundamental forces of the universe, how can you or any scientist dismiss it as having no effect on our earth, I just don’t know.

    • Have you heard of the Chaos affect? Buttlefly flaps wings.. hurricane … We are all connected in somewhere to the fabric of the universe and are one, entanglement – universe has been entangled as a single system right from the Big Bang, ergo the moon can and does have an effect on mass-murder, earthquakes, and sadly terrorism, etc.

      I’ve previously explained (halfway through this comment) that quantum entanglement isn’t a license to speculate wildly.

      Notice Japan’s earthquake and Tsunami and riots around the world and economic collapse. No one is an island here.

      I’ve noticed those things, but haven’t noticed how they have anything to do with the moon.

      Gravity is one of the 4 fundamental forces of the universe, how can you or any scientist dismiss it as having no effect on our earth, I just don’t know.

      Ironically, you wrote this sentence right after this comment where I describe how the moon’s gravity not only causes tides in the ocean but also body tides in the continents of our earth. I then mentioned that this concept is well known in the mainstream scientific community. After decades of study, the effects of body tides on earthquakes just turned out to be relatively insignificant: “Practically speaking, you’ll never see any effect of lunar perigee. It’s somewhere between ‘It has no effect’ and ‘It’s so small you don’t see any effect.'”

      Furthermore, I’ve explained how the moon’s gravity causes tidal bulges on both sides of our earth, and how these tidal bulges are not only slowing down our earth’s rotation, they’re also causing the moon to move away from our earth.

      In fact, I’ve pointed out that my day job is using GRACE satellite data to refine our estimates of global ocean tides, which once again are caused by the moon’s (and the sun’s) gravity interacting with the coastlines/bathymetry of the ocean basins.

      Scientists are well aware that gravity is one of the four fundamental forces in the universe, and that the moon’s gravity has effects on our earth. We just disagree with astrologers when they make unscientific and unfalsifiable statements about the moon causing mass-murder and terrorism.

  7. Glen Mackie posted on 2011-03-29 at 20:12

    Does this wobble take into consideration the Earth’s wobble when photographing it? How do you eliminate the effect of our own wobble and get a clear picture of how the moon wobbles? (apologies if this is a stupid question). Thank you.

    • I’m not sure what you mean by the “Earth’s wobble”. The observed “wobble” of the moon is a vague term I used to refer to the fact that its orbit around Earth is elliptical, so it’s not always at the same distance from Earth or moving at the same speed.

      Technically, this is true for the Earth as well, in the sense that Earth’s orbit around the Sun is slightly elliptical (but note that this has nothing to do with the seasons.) However, that ellipticity has no effect on photographing the moon because in that sense the Earth-moon system moves as a single unit.

      There are phenomena like the Chandler wobble which very slightly affects Earth’s axis of rotation over a period of ~1.2 years. Earth’s axis of rotation also “nutates” over a period of ~18.6 years, and precesses over a period of ~26,000 years.

      These phenomena are relevant to geophysicists and professional astronomers, but:

      1. They’re so tiny that they don’t affect amateur photography of the moon.
      2. They change so slowly compared to the moon’s ~28 day orbital period that even if they were much larger, they still wouldn’t affect pictures taken over a single orbit of the moon.

      Note that I didn’t make that movie; it was made by Tom Ruen. His page has many more cool photos that are worth checking out.

      Thanks for asking the first genuine question in years, which is really the only criterion needed for a question to not be stupid. You’re clearly trying to understand the universe rather than trying to justify a pseudoscientific preconception, which makes you the one-eyed man in this absurd kingdom of the blind…

  8. mikal posted on 2011-09-27 at 06:25

    what’s offensive about western science is its arrogance.
    you don’t know what intuition is, and that is the tragic flaw of western thinking and certainly of western science. intuition plays a part in astrology — the astrology that Kepler, Galileo and many of your other predecessors in science came from. intuition. do you know what it is?

    i’m done trying to percieve you and yeah, i did come in from looking up moon wobbles. but it does say “dumb” at the top.

    yours is the sort of scientist that gives all their energy to the military-industrial complex and then swears that they are not personally responsible for the atrocity. a form of evil, i think i can say that.

    empiricists are limited thinkers who assume that anything they cannot find evidence for could not exist. often the fault is in their closed minds…

    • I’m sure my colleagues from China, Taiwan, Japan, Korea, Russia, Pakistan, the Czech Republic, India, Croatia, Australia and New Zealand will be relieved to hear that they’re not offensive, arrogant, closed-minded, hypocritical, evil limited thinkers.

      But, like me, I think they’ll be puzzled as to what “western” science is. There is only science: the attempt to explain all conceivable experimental evidence with a self-consistent theory that requires the fewest possible number of assumptions.

      intuition. do you know what it is?

      Yes. Several years ago I said: I’m not fundamentally opposed to using intuition to solve mysteries. Choosing hypotheses to test is notoriously subjective, so “gut instinct” serves well in that capacity. But intuition is only the first step towards knowledge; that intuited hypothesis still needs to be subjected to rigorous scrutiny.

  9. Tony V. posted on 2012-01-29 at 22:54

    Thanks for this great information. I’d seen this sequenced video before, but couldn’t seem to find the explanations behind it. I am curious to know if theoretically there would ever be a point in time that, as the orbit of the moon increases, the closer proximity of the moon’s orbit with that of Venus would cause orbital disturbances between them. My intuition is that the tidal effects that are causing the moon’s orbit to increase would be diminished due to distance long before the orbit would increase that much. My second guess is that before the moon’s orbit increases that much, our sun will expand into a red giant, consuming all the inner planets.

    Thanks again for the insight!

    Tony

  10. David posted on 2012-05-09 at 13:27

    I’ve heard and seen a lot of “end of world” stuff online lately talking about how the moon is shifting poles, etc. Although I don’t buy into this kind of hysteria, I did do a little online moon pick comparisons and there does appear to be a much more significant shift of the 2 dark spots from the right side all the way to the top. Recent moon pictures of the Super Moon on May 5 2012 show this most significantly as compaired to your moon video where he spots are on the right. Now they are on the top. This seems to be about a 90 degree shift. I’s say that’s significant. I am sure if there was anything to worry about every amateur and professional astronomer worldwide would be talking about it. I am sure it is basically a case of ignorance. Can you educate me?

    • If nothing else, GRAIL would’ve noticed a 90 degree shift in the moon’s rotational axis. Conservation of angular momentum strongly argues against such an event.

      • phil w posted on 2016-01-24 at 06:24

        Within the course of a six hour span, I witnessed and photographed the moon rotate its face over 90 degrees. I have seen the Tycho crater point to the 4 o’clock position, as well as the 7 o’clock position only a few hours later. I am not refering to libration, and I understand your statement about angular momentum, but I know what I saw.
        Is there any explanation you can come up with for the moon behaving as described? A ‘perturber, perhaps?’ I have never seen anything like it in all my previous years of moon-watching.
        advTHANKSance

      • Either you accidentally rotated your camera, or there was a massive violation of momentum conservation which went unnoticed by all the other cameras and telescopes on Earth, and unnoticed by satellites orbiting the Moon. Hmm…

      • phil w posted on 2016-01-25 at 22:13

        Thank you for answering.
        http://www.nbnweathershots.com.au/content/full-moon-rising-behind-tree-covered-mountain
        http://www.miguelclaro.com/wp/?portfolio=the-moon-behind-the-trees
        The trees ensure the angle, almost 120 degrees of rotation, not mirrored.
        Many examples exist. I have witnessed it over the course of an evening, I’ve worked nights and I had never seen anything like this. I’ve been a sky-gazer for decades. I’m not attacking mainstream theory, I’m curious.
        And my camera is on a tripod.

      • The ground under your tripod rotated. Consider a simple example where the Moon lies motionless in the Earth’s equatorial plane. Imagine standing on the equator and taking a picture of the Moon rising above the eastern horizon. If your camera is on a vertical tripod then the Moon’s north pole would be on the left side of the image.

        Then wait ~12 hours and turn the tripod around to take another vertical picture of the Moon setting on the western horizon. The Moon’s north pole will now be on the right side of the image because the ground under your tripod rotated ~180°, forcing you to turn the tripod around ~180° to take a picture of the western horizon.

        So the Moon would appear to rotate even if it were perfectly stationary, just because the ground under your tripod is rotating.

      • phil w posted on 2016-01-27 at 03:31

        Could you then please explain to me how rotating my camera 180 degrees about the Y axis has rotated the moon 90+ degrees about the Z axis ??
        I may have to make a .gif.

      • Please think carefully about the geometry in that example. In that case, the apparent rotation of the Moon is 180° because you’re standing on the equator. There, the vector defining “vertical” completely changes direction if you wait half a sidereal day. If you stand on the north or south pole instead, the vector defining vertical there never moves, so the apparent rotation of the Moon would be 0° in that case.

        If you’re standing in the mid-latitudes the “apparent rotation” of the Moon between moonrise and moonset will be between the equatorial 180° and the polar 0° “apparent rotation”.

    • I didn’t call you names, but your attempted association is disingenuous and repulsive. “…he probably doesn’t object…” PROBABLY being the key term here. Grow up. You come off like a maligned child. [Phil W]

      Phil, you’re the one who said “perhaps there is a reason” that throwing accusations at me seems to be a popular hobby. You said that after I linked those accusations. That’s why I wondered if you actually thought “perhaps there is a reason” for all those accusations. You still haven’t actually said that you object to those statements which you said “perhaps there is a reason” for. Do you still think there’s a reason for those statements, or do you retract your claim? Because your language doesn’t make that clear.

      You don’t remember accusing me of acting “like a hack” and “killing the reputation of legitimate scientists”? Exactly how do you think your position differs from that of Rujiel or Jane/Lonny Eachus? Again, if I actually were doing what Phil W baselessly accuses me of, why not just take out all that anger frustration on me?

      Just to clarify, the rotation I noticed WAS every night, but I had never seen/noticed the moon in this position before this year, which is why I assumed some perturbation. [Phil W]

      Since you said you’d “never seen anything like it” in all your previous years of moon-watching, do you see why I initially dismissed the possibility that you and David were describing the apparent rotation of the Moon based on the Earth’s rotation?

      I know full well that I’m not addressing fellow academics but lay-people. However, I think even lay-people are capable of understanding that point. Are you, Phil?

      “Phil’s response mystifies me. He didn’t say (and still hasn’t said) if he agrees with my example above.” [Dumb Scientist]

      My response would only mystify if one didn’t understand the difference between rotation and translation. Do you understand axis/axes? [Phil W]

      You still haven’t said if you agreed with my example above. So it’s still not clear if we agree on the basic physics I described. Again: do you agree with my example above? Yes or no?

      I understand the difference between rotation and translation, and axis/axes. Thanks for asking! I really enjoy your fascinating and obviously productive questions which are clearly motivated by your genuine curiosity and good faith. At least, to the same extent as all the charming questions from these charming fellows.

      But your questions still don’t explain why you started asking about Y and Z axis rotations without even explaining how you’re defining the directions “Y” and “Z” in this context.

      Again: do you agree with my example above? Yes or no? Then we can start to define Y and Z axes so your next response isn’t as mystifying.

      As for the rest, you keep introducing new terms. The reason you come off as a hack is that you didn’t answer my question, or David’s question until I pressed you on it. Then you did some research. Claiming to have coined the term ‘apparent rotation’ is the clincher. [Phil W]

      I claimed that I independently called an “apparent rotation” an “apparent rotation”. That’s a natural term for a rotation that only apparently occurs in “non-inertial space” but doesn’t happen in “inertial space”. None of those are new terms. But your repetitive accusations that I “did some research” and am “just looking this stuff up as it comes” are simply bizarre.

      First of all, you’re wrong. If you don’t understand why a scientist might call an “apparent rotation” an “apparent rotation” then please think about those words for a few seconds. If that doesn’t work, try thinking about them for a few minutes. Etc.

      Secondly, you have absolutely no evidence to support your bizarre accusation. None whatsoever. It’s the same behavior I see from other “conspiracy theorists” who become convinced of some nonsensical accusation without any evidence. All they seem to need are insinuations and suspicion to support their accusations.

      Third, the fact that you seem determined to keep repeating your baseless accusation is bewildering. Why is it that internet trolls focus on bizarrely irrelevant accusations? Why not try to learn about science instead?

      Don’t get your knickers in a knot just because I don’t accept your explanations. I asked someone else to confirm your conclusions, anyhow. They agreed that your explanations were contradictory and that the video I linked to best demonstrated the principle. I have my answer, and thanks for trying, but what you don’t get is that you are not addressing fellow academics but lay-people. If you learnt to express yourself more clearly, you might not frustrate so many. Best of luck with your short-comings. [Phil W]

      Gosh, thanks! Exactly how were my explanations contradictory? Again, the Moon’s rotation axis doesn’t rotate. Conservation of momentum strongly argues against such an event. Its axis might seem to rotate if you accidentally rotate your camera, but that’s like spinning on a merry-go-round and thinking the world is spinning instead. (That’s the lay-people difference between an “inertial” and “non-inertial” viewpoint.)

      Presumably your explicitly claiming you’d “never seen anything like it” and stressing all your previous years and decades of moon-watching is the example of “expressing yourself more clearly” which I should aspire to, so as not to “frustrate so many”?

    • Could you then please explain to me how rotating my camera 180 degrees about the Y axis has rotated the moon 90+ degrees about the Z axis ?? [Phil W]

      Since Phil refuses to define his Z and Y axes, let’s do that for him. In most geophysics applications, the Z axis is Earth’s rotational axis. Let the Y axis point from Earth to the Moon. To form a right-handed coordinate system, the X axis points to the spot on the equator where a person would see moonrise.

      This means the equatorial “vertical” direction vector at moonrise/moonset points directly along the positive/negative X axis. Note that a 180° rotation around the Z axis flips the equatorial “vertical” direction vector.

      Now consider lying on a merry-go-round on the equator when the Moon is exactly overhead. This way, the merry-go-round’s vertical axis of rotation is the Y axis. Begin by lying down on the merry-go-round with your feet toward the center and your head pointing due west. This way, your body points along the positive X axis, just like it did when you were standing vertically at moonrise.

      Now consider rotating the merry-go-round 180°, which is a rotation around the Y axis. When you stop, your body will point along the negative X axis, exactly the same way as when you were standing vertically at moonset.

      No they are not the same. First is a rotation about the Y axis, second is a rotation about the Z axis, and the third is not even rotational. How can you say they are the same? [Phil W]

      Please think carefully about the rotations I just described about the Z and Y axes. Those show that my original equatorial moonrise-to-moonset example (rotation about Z axis) makes the Moon apparently rotate in exactly the same way as the merry-go-round example (rotation about Y axis).

      My response would only mystify if one didn’t understand the difference between rotation and translation. Do you understand axis/axes? [Phil W]

      Maybe your response wouldn’t mystify if you’d define your axes. The Y and Z axes defined above show that my original example had already explained to you how rotating your camera 180 degrees about the Y axis has rotated the moon 90+ degrees about the Z axis.

      That’s one reason why your response was mystifying. In addition, you still haven’t even said if you agree with the example, which makes communication impossible.

      That’s why I tried to be slightly more explicit, pointing out that at non-equatorial latitudes the component of the “vertical” direction vector pointing in the Z direction doesn’t rotate as the Earth rotates. So only the projection of the “vertical” direction vector onto the XY-plane causes the Moon’s face to apparently rotate. That’s why I said the Moon’s face wouldn’t apparently rotate if one were standing at Earth’s north or south pole; the “vertical” direction vector there has zero projection onto the XY-plane.

    • email from Phil W posted on 2016-02-09 at 08:31

      Sir, breathe.
      This isn’t a legal matter. Don’t make it one.
      You were wrong and you don’t want to admit it… I get it.
      Botttom line – David didn’t get an answer which I only got after asking repeatedly.
      .
      You’re not alone, none of the legitimate astonomers I’ve asked wanted to answer my question, perhaps because they didn’t quite understand it, or couldn’t visualize it, or just couldn’t explain it. I wanted to be able to do all those things.
      .
      The animation at the top of your page (Wikipedia) shows one image per day. If it showed one image per hour, the animation would be quite different. So how come I can’t find one like that anywhere? Why is that animation not also presented? It would seem far more interesting. Perhaps you just want to avoid the flood of questions about the combination of an impossibility in angular momentum and an optical illusion.
      .
      Understand that when you present something which does not match my first-hand experience, I question it. Your animation did not match what I saw. Your answer was never definitive. I wanted to understand an anomaly I had witnessed, not start a feud. I found my own answer, later.
      .
      I don’t know if you’re a hack scientist or a hack blogger, either way, I didn’t like your answer. You should learn to live with disappointment, it seems to suit you.
      You had, though indirectly, led me towards the answer to my question.
      Having said that, I truly believe that you over-estimate the sway your opinion holds over me.
      .
      Mondoweiss? Paranoia much? I don’t think you matter that much to other people either, internet astronomer, despite any letters you may wear. Grow up; don’t let ’em get such a rise out of you.
      You’ve acted badly throughout this whole ordeal.
      .
      Goodbye Mr. Bryan Killett.
      PhilW
      .
      ps_ Remove me from any list, database, or group… mailing or otherwise.

    • So you still refuse to define the Z and Y axes that you brought up? Were your axes different than the ones I described?

      Sir, breathe. This isn’t a legal matter. Don’t make it one. [Phil W]

      What a fascinating threat. How could I “make it one”? You came to my website and called me a hack who’s “killing the reputation of legitimate scientists” with my “ridiculous methods”. Your malicious accusations even included claims of “destroying credibility”.

      And now, after throwing around all sorts of libelous accusations, you’re sagely advising me not to make it a legal matter. Fascinating.

      You were wrong and you don’t want to admit it… I get it. [Phil W]

      Really? Because I just defined the Z and Y axes that you brought up but keep refusing to define. Those Z and Y axes show that my original example had already explained to you how rotating your camera 180 degrees about the Y axis has rotated the moon 90+ degrees about the Z axis.

      In other words, I’d already answered your question before you asked it. Which is one reason why your question was mystifying.

      You’re not alone, none of the legitimate astonomers I’ve asked wanted to answer my question, perhaps because they didn’t quite understand it, or couldn’t visualize it, or just couldn’t explain it. I wanted to be able to do all those things. [Phil W]

      Did you ask the “legitimate astronomers” the same way you asked me? By stressing that you’ve “never seen anything like it in all your previous years of moon-watching”? Maybe you should consider another possibility: those legitimate astronomers didn’t think you were talking about something that happens every night, considering you’ve been a star-gazer for decades.

      The animation at the top of your page (Wikipedia) shows one image per day. If it showed one image per hour, the animation would be quite different. So how come I can’t find one like that anywhere? Why is that animation not also presented? It would seem far more interesting. [Phil W]

      If it showed one image per hour, the background would be constantly changing from the black night sky to the blue daytime sky. That might be why you can’t find one like that anywhere. Not sure why that animation seems “far more interesting” to you. Again, if the camera’s orientation were held fixed in inertial space then the Moon wouldn’t apparently rotate.

      Update: Again, here’s a good example of what it looks like when someone doesn’t accidentally rotate their camera because they compensated for the fact that the ground under the tripod rotated.

      Perhaps you just want to avoid the flood of questions about the combination of an impossibility in angular momentum and an optical illusion. [Phil W]

      Actually, I just want to avoid a flood of libelous and malicious accusations. You know, like people coming to my website and baselessly accusing me of being a childish hack who’s destroying credibility and “killing the reputation of legitimate scientists” with my “ridiculous methods”.

      Polite questions, on the other hand, are always welcome. It’s still unclear why you think I’d want to avoid questions about angular momentum. Again I must stress that my initial statement to David still holds true: conservation of angular momentum strongly argues against a 90 degree shift in the moon’s rotational axis. Its axis might seem to rotate if you accidentally rotate your camera, but that’s like spinning on a merry-go-round and thinking the world is spinning instead.

      Grow up; don’t let ’em get such a rise out of you. You’ve acted badly throughout this whole ordeal. [Phil W]

      How fascinating. You show up uninvited and call me a hack who’s “killing the reputation of legitimate scientists” with my “ridiculous methods”. Your malicious accusations even included claims of “destroying credibility”.

      Presumably that’s how I should have acted, so Phil wouldn’t accuse me of “acting badly”? Instead, I answered Phil’s questions despite his accusations, and never responded to Phil in kind.

      Phil, I never called you a hack. I never maliciously accused you of “killing the reputation of legitimate scientists” or “destroying credibility” or acting like a maligned child. Not once. Even after you repeatedly did that to me. Instead, I repeatedly turned the other cheek. Presumably in Phil’s mind that constitutes “acting badly” but Phil hurling all those baseless and libelous accusations is just proof that Phil is a grown up who’s not acting badly?

      Phil, do you live in Bizarro World?

    • Piss Off. I’m not refusing to do anything. I’m ignoring you because I got my answer (no thanks to you) and now I’m moving on with my life. I strongly suggest you do the same. You seem to over-estimate the importance I place in you and your opinion and your feelings. This badgering is not professional at all. Now FUCK OFF and leave me alone or I’m calling my lawyer. [Email from Phil W]

      Again, you’re refusing to define the Z and Y axes you brought up. And you’re way too much of a coward to call your lawyer. Too bad. That would’ve been hilarious.

  11. M. Vang posted on 2012-08-06 at 22:01

    I came here looking for the wobble detected via laser bouncing off reflectors placed on the moon during Americas moon landings. The “wobble” I was searching for is thought to be caused by a large impact on the moon.

    Similar to one of your previous comments, I was wondering how this measurement of “wobble” might take into account whatever sort of wobble the Earth might have. Instead I found this site, which seems a rich comedy in the study of Astrology. I find it especially humorous that the name of Kepler was used to support Astrology. His strange notions led him to believe for years in celestial spheres, in privileged, perhaps sacred, perfect solids which hearken back to Plato. He only came to the correct answer of elliptical orbits after having the bravery to accept that the observed measurements of the orbits out weighted any personal desire that his pet theory would be correct.

    If you believe in astrology and use Kepler to support it, I suggest you learn more about the man. At the least watch the Carl Sagan Cosmos series in full.

  12. George (not an astronomer, just a safety guy) posted on 2012-08-20 at 15:12

    Great discussion! However, it’s important to note that there have been times when accepted scientific ideas have been overturned, and respected scientists have been completely wrong.

    Newton was a rigorous scientist. Much of modern physics relies on the laws of motion that he quantified. But as it turns out he was a little overconfident when he named his ‘universal’ law of gravitation. As Einstein showed early in the 19th century, that law isn’t quite universal. It needed an adjustment in circumstances that Newton couldn’t possibly have anticipated.

    Lord Kelvin was another overconfident scientist. Despite being responsible for some great work, he stepped outside his area of expertise to declare that radio would never be more than a curiosity, and that heavier than air flight was impossible. Today, both statements seem ridiculous. They don’t diminish his other work, but they serve as a reminder that you can’t know everything.

    To be clear, I’m not defending astrology. Any field of study that relies on coincidence and conjecture to ‘prove’ its postulates is not science, any more than an ancient priest’s assurance that, since the sun came back after every solstice when a ritual dance was performed, the dance is what brought back the sun.

    But we must always allow for the possibility that widely accepted ideas may need to be refined, or even discarded altogether, based on new evidence.

    On the other hand, when the vast majority of the world’s scientists say one thing, they’re much more likely to be right than wrong!

  13. Carlos posted on 2012-09-08 at 05:22

    Great site, clear well written science. Much appreciated.
    Also, I’m amazed that you bothered to answer the nutters.

  14. Don posted on 2012-12-23 at 20:25

    I’m kind of interested to know if the moon’s actual orbital wobble around the earth, not the visual effect wobble but it’s actual path around our planet, has reached it’s apex? I had read somewhere, not sure where, that 2012 (no not refering to Mayan predictions which we all know now not to be true finally) that we have 3 known wobble’s which all reach their apex, moon orbital path wobble, actual earth rotational wobble and earth orbital path (around the sun) wobble. Just wondering if you might know if the event had already occurred or is still due to occur.

  15. Chris W posted on 2018-01-30 at 06:48

    Thanks for putting in the time to write this article. After a recent askreddit from NASA on the LRO, I was confused by the apparent ‘wobble’ in the great visualizations at https://svs.gsfc.nasa.gov/4604

    Thanks also for your attempts to engage the folks above. My father is one of them, and I pretty much can’t communicate with him anymore.

  16. Simon Boardman posted on 2018-04-04 at 19:18

    The disagreement I have is more than fundamental…your article appears to be based entirely on deception. You describe this animation as photos taken from earth. This does not appear to stand up to scrutiny based on my observations of the Moon from the earth (I am not an astronot). Two things strike me as untrue about these supposed photos. 1. The Moon in my experience is never illuminated in the way a true sphere is illuminated ie The Moon does not have a “hot spot” with increasingly shaded light towards the edges. Your pictures have clearly been artificially and artistically shaded as an artists impression of how a ball would normally appear in accordance with standard logic but this is not the reality any observer of the night sky would actually observe. 2. any actual photo of the Moon would not allow you to see any features of the darkened portion where as your Gif is showing Moon surface features in the darkened portion.
    You appear to be involved in a scam…a clear deception, trying to pass this CGI off as reality.

  17. Andrew posted on 2018-11-27 at 05:54

    Quote:- “The Moon’s rotation rate matches its average orbital speed (which is why we only see one face of the Moon)”

    Don’t be daft, the moon doesn’t rotate on it’s own axis, not at all, what makes you think it does? before you answer try to be sure that your answer isn’t “cos everyone else says it does”. Because I can prove beyond any doubt that the moon does not rotate on it’s own axis. I’m thinking of publishing a paper on this subject to highlight just how stupid the scientific community can be. It reminds me of the mathematical model that was created to prove that the sun and all the planets rotate around the Earth. If I’m right (and I am) it brings into question another established scientific theory. How did the scientists explain the amazing coincidence that the moon rotates on its axis exactly once per orbit. Tidal locking, lol, really?, I don’t think so.

  18. Dan from sc posted on 2018-12-23 at 06:32

    i watched the moon rotate during the night 90 degrees. i noticed when we had half moon. the shadow started on the left like it supposed to but through the night the shadow was now on top. the rabbit years that were at the top right were now at the bottom right at the end of its setting.

    yesterday’s full moon i watched rabbit ears top right. and as I am typing this the next morning. i see the rabbit ears bottom right. that’s a 90 degree rotation through the night. i cant sleep till i get a reasonable answer. and no I have not changed perspective. I’m at my house on my porch.

    • Saying you “have not changed perspective” would only be true here if your viewpoint were stationary in inertial space (which wouldn’t be rotating). So a physicist would compare the moon’s orientation to something which is stationary in inertial space, such as the fixed stars. (In other words, look at the stars right next to the moon and make sure those stars are oriented in the same way each time you look at the moon. If there’s a bright blue star directly above the moon at one time, make sure you rotate your head so that same bright blue star is directly above the moon at any other time you look at the moon.) If you do that, you’ll notice that the moon’s axis remains oriented the same way with respect to those fixed stars.

      Update: Here’s a good example of what it looks like when someone doesn’t accidentally rotate their camera because they compensated for the fact that the ground under the tripod rotated.

      Surprisingly, it seems like some people implicitly consider their local “vertical” direction to be fixed in inertial space. So they ignore the fixed stars and simply try to see if the moon appears to be rotating relative to the local “vertical” direction defined by nearby trees.

      The problem here is that the local “vertical” points in different directions at different times because the Earth rotates on its axis. (The only exceptions would be if you live at the north or south poles.) In other words, if you compared the moon’s orientation to the local “vertical” direction, you accidentally rotated your viewpoint because the Earth itself rotates. As a result, the moon will seem to rotate if you compare its orientation to the local “vertical” but this is only an “apparent rotation” which is actually caused by the Earth’s rotation.

  19. Dan from sc posted on 2018-12-23 at 06:33

    why doesn’t the moon cause tides on lakes?

    • Look at this diagram of ocean tides. The bulge in the ocean directly below (and opposite) the moon exists because the moon’s gravity pulls water there from places far away where the moon’s gravity doesn’t point in a vertical direction. So ocean tides can only exist if water can flow long distances. Lakes simply aren’t large enough for this to happen, so even the Great Lakes have tidal amplitudes that are less than 5 cm high.

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