Yesterday we had a sort of a review of the lunar postings so far and a look at how the orbital changes are not quite as expected. That the lunar orbit is “wrong” – per some folks. Also a touch on the history of tides and that some of the very earliest writings are claiming much stronger tides than at present. There was also a link to a WUWT article about about the way tides are much larger during certain alignments of sun, moon, and earth with particular orbital conditions (perigee). Including calculations that tides then could be significantly larger. Between 1.5 x and 2 times present. This would tend to wash more warm water under the North Pole ice cap and help break up the ice. It would also cause large changes in ocean mixing of water levels and change both ocean surface temperatures, and through them, air temperatures.
I raised the question of other effects and that, perhaps, the lunar orbit might have a greater range than we presently think; and that might lead to some truly extreme tides. Perhaps even as extreme as the earliest recorded observation (that has been rejected by some as fanciful due to the large size.)
So then I went off looking for any evidence for just “how big” variations from expected might be. Along the way I found some Wiki articles that give a general idea how much the moon changes position. First I’ll put some of that information here, then I’ll put some bits from the paper on historic eclipse variation.
When the moon wanders around in it’s 18.6 (ish) year cycle, it has several minor cycles and a major one. Each month, the moon looks like it moves north and south, stopping at each end in a ‘standstill’. Much like the sun has a solstice, the moon also changes direction, but it is called a standstill. There are times when those standstill times are at greater range than others. Those are the Major Standstill. That cycle marks the end of the 18.6 year cycle. Now remember that the earth rotations are nearly perfectly synchronized after three such cycles; so each cycle has the maximum tide force happening over a different 1/3 of the globe, then on the third one it is back over the same bit of the planet surface. This means that, for example, a Major Standstill that happens over the mid-Pacific ocean will not happen again over that patch of water for 3 x 18.6 years, or about 55.8 years. It is my belief that this is the reason there is an “about 60 year” cycle in the weather of the planet. It is all about tides and ocean mixing.
So lets get some numbers and background.
At a major lunar standstill, which takes place every 18.6 years, the range of the declination of the Moon reaches a maximum. As a result, at high latitudes, the Moon’s greatest altitude (at culmination, when it crosses the meridian) changes in just two weeks from high in the sky to low over the horizon. This time appears to have had special significance for the Bronze Age societies who built the megalithic monuments in Britain and Ireland, and it also has significance for some neo-pagan religions. Evidence also exists that alignments to the moonrise or moonset on the days of lunar standstills can be found in ancient sites of other ancient cultures, such as at Chimney Rock in Colorado and Hopewell Sites in Ohio.
What this says is that the moon reaches an extreme range every 18.6 years, and offset from that it reaches a minimal range of N / S wander on the 1/2 way point. Now I just have to think that having the moon stay relatively close to the equator has to be very different for tides when compared with having it rush from further north to further south in a couple of weeks.
That the ancients had noticed this time was “special” just causes me to think all the more that there is something here to track down. Those ancients didn’t have much to do other than observe carefully and think about what they saw. They tended to be careful about what was (literally) cast into stoneworks. So we need to be particularly aware of Standstill, and especially of Major Standstill. Got it.
At this point, a minor digression on lunar orbit…
The moon orbits the sun. Unlike most moons, it does not orbit in the plane of the equator of the planet (i.e. Earth) but instead orbits near the ecliptic. This matters since the Earth axis is tilted to the ecliptic. That means the moon seems to ‘bob’ up and down relative to the Earth. This matters since it is a bit different from most moons and planets. The Sun influences the lunar orbit more than does the Earth, and the complexities of the lunar orbit come from it being disconnected from the Earth equator. Much of our tides, and through them, climate and weather come from that fact. More on that later.
Unlike the stars, the Sun and Moon do not have a fixed declination. As the Earth travels its annual orbit around the Sun, with its rotational axis tilted at about 23.5° from the “vertical” (a line perpendicular to the orbit), the Sun’s declination changes from +23.5° at the northern hemisphere Summer Solstice to −23.5° at the northern hemisphere Winter Solstice. Thus, in the northern hemisphere, the Sun is higher in the sky and visible for a longer period of time in June than it is in December. This is the cause of the Earth’s seasons.
The Moon also changes in declination, but it does so every lunar nodal period or 27.212 days. So it goes from a positive declination to a negative one in under two weeks. Thus, in under a month the Moon’s altitude at its culmination (when it is due south on the meridian) can move from being high in the sky, to low over the horizon, and back again.
The Moon’s maximum and minimum declination also varies because the plane of the Moon’s orbit around the Earth is inclined by about 5.14° to the ecliptic (the plane of the Earth’s orbit around the Sun), and the direction of lunar orbit inclination gradually changes over an 18.6-year cycle, alternately adding to or subtracting from the 23.5° tilt of the Earth’s axis. As a consequence, the maximum declination of the Moon varies from roughly (23.5° − 5°) = 18.5° to (23.5° + 5°) = 28.5°. As a result, at minor lunar standstill, the Moon will change its declination during the nodal period from +18.5° to −18.5°, which is a total movement of 37°. Then, 9.3 years later, during the major lunar standstill, the Moon will change its declination during the nodal period from +28.5° to −28.5°, which is a total movement of 57°, which is enough to take its culmination from high in the sky to low on the horizon in just two weeks (half an orbit).
Now think about that for just a minute. Because the Moon does not orbit the Earth at the equator, but orbits the Sun along with the Earth as a binary planet, it wanders up to 57° relative to the oceans. Or as little as 37° at other times. 20° of variation. Think 20° more or less tidal pull toward the poles or away from them just might make a little bit of difference to how big the tides are? To how high “average sea level” might be in an area? To how much tidal mixing of cold water into surface waters happens? To how much water moves into the northern oceans or into the southern oceans? To ENSO? To how much ice shelves at the poles break up? To, basically, long term average weather? (Mistakenly called climate by most “climate scientists”. Climate changes on million year scales. Weather changes on decade, century, and millennium scales.) In short, there is a very large periodic perturbation of the Earth systems and oceans, with periods of roughly 9, 18, 56, 179 and even 1800 years (and others we’ve not talked about). This drives much of the natural variation of our weather and 30 year average of weather called ‘climate’ by some. On longer cycles the same effects happen, but due to other cycles such as longer term variations in obliquity, eccentricity (of earth and moon orbits), tides and even solar output of energy and the distribution of it as UV vs other wavelengths. It is all natural cycles and oscillations of our natural world.
Some Other Lunar Bits
During the June Solstice the Ecliptic reaches the highest declination in the southern hemisphere, −70′-130′ When at the same time the ascending node has a 90° angle with the Sun in the southern hemisphere, the declination of the Full Moon in the sky reaches a maximum at −23°29′ – 5°9′ or −28°36′. This is called the major standstill or Lunistice in the southern hemisphere. Nine and a half years later, when the descending node has a 90° angle with the December Solstice the declination of the Full Moon in the sky reaches a maximum at 23°29′ + 5°9′ or 28°36′. The other major standstill or Lunistice, this time in the northern hemisphere.
Whenever you see an ‘about 9 year’ cycle for things, think of a lunar tidal influence…
So who orbits what?
In representations of the Solar System, it is common to draw the trajectory of the Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of the Earth. This could give the impression that the Moon circles around the Earth in such a way that sometimes it goes backwards when viewed from the Sun’s perspective. Since the orbital velocity of the Moon about the Earth (1 km/s) is small compared to the orbital velocity of the Earth about the Sun (30 km/s), this never occurs. There are no rearward loops in the Moon’s solar orbit.
Considering the Earth–Moon system as a binary planet, their mutual centre of gravity is within the Earth, about 4624 km from its centre or 72.6% of its radius. This centre of gravity remains in-line towards the Moon as the Earth completes its diurnal rotation. It is this mutual centre of gravity that defines the path of the Earth–Moon system in solar orbit. Consequently the Earth’s centre veers inside and outside the orbital path during each synodic month as the Moon moves in the opposite direction.
Unlike most moons in the Solar System, the trajectory of the Moon around the Sun is very similar to that of Earth. The Sun’s gravitational effect on the Moon is over twice as great as the Earth’s on the Moon; consequently, the Moon’s trajectory is always convex (as seen when looking Sunward at the entire Moon/Earth/Sun system from a great distance outside the Earth/Moon solar orbit), and is nowhere concave (from the same perspective) or looped
This matters. Were the Moon to orbit the Earth at the equator, our weather and climate would be much different and far less variable. Not only does the angle range vary by 20°, but the distance from the Earth changes too. Tides are much more variable than one person sees in one lifetime.
Note that this distance graph is not including the effects of the 18.6 year or longer year cycles. Things change. A Lot. Any climate model that does not allow for this highly variable mixing of the oceans and tides is a model that is broken and can not work correctly.
Isaac Asimov suggested a distinction between planet–moon and double-planet structures based in part on what he called a “tug-of-war” value, which does not consider their relative sizes. This quantity is simply the relationships between the masses of the primary planet and the Sun combined with the squared distances between the smaller object and its planet and the Sun:
tug-of-war value = m1⁄m2 × (d1⁄d2 )^2
where m1 is the mass of the larger body, m2 is the mass of the Sun, d1 is the distance between the smaller body and the Sun, and d2 is the distance between the smaller body and the larger body. Note that the tug-of-war value does not rely on the mass of the satellite or smaller body.
This formula actually reflects the relation of the gravitational effects on the smaller body from the larger body and from the Sun. The tug-of-war figure for Saturn’s moon Titan is 380, which means that Saturn’s hold on Titan is 380 times as strong as the Sun’s hold on Titan. Titan’s tug-of-war value may be compared with that of Saturn’s moon Phoebe, which has a tug-of-war value of just 3.5. So Saturn’s hold on Phoebe is only 3.5 times as strong as the Sun’s hold on Phoebe.
Asimov calculated tug-of-war values for several satellites of the planets. He showed that even the largest gas giant, Jupiter, had only a slightly better hold than the Sun on its outer captured satellites, some with tug-of-war values not much higher than one. Yet in nearly every case the tug-of-war value was found to be greater than one, so in every case the Sun loses the tug-of-war with the planets. The one exception was Earth’s Moon, where the Sun wins the tug-of-war with a value of 0.46, which means that Earth’s hold on the Moon is less than half the Sun’s hold. Since the Sun’s gravitational effect on the Moon is more than twice that of Earth’s, Asimov reasoned that the Earth and Moon form a binary-planet structure. This was one of several arguments in Asimov’s writings for considering the Moon a planet rather than a satellite.
We might look upon the Moon, then, as neither a true satellite of the Earth nor a captured one, but as a planet in its own right, moving about the Sun in careful step with the Earth. From within the Earth–Moon system, the simplest way of picturing the situation is to have the Moon revolve about the Earth; but if you were to draw a picture of the orbits of the Earth and Moon about the Sun exactly to scale, you would see that the Moon’s orbit is everywhere concave toward the Sun. It is always “falling toward” the Sun. All the other satellites, without exception, “fall away” from the Sun through part of their orbits, caught as they are by the superior pull of their primary planets – but not the Moon.
— Isaac Asimov
Simply put, we must look to the Sun to know what perturbs the lunar “orbit” of the Earth. The difference between the Earth orbit and the Moon orbit of the Sun cause all sorts of subtle things to happen on Earth that do not happen on other planets from their moons. Including many interesting variations in our tides, currents, weather, and climate cycles.
The Value of Old Data, Unadjusted and Unmolested
With that context, I ran into this interesting paper that looks at actual recorded eclipses vs those predicted by NASA model computer codes. The computer models are wrong. By definition. The observations are right. These folks in India did an absolutely stellar job of doing real and professional science. Not polluted by Political Agenda. Not with the answer predetermined. NOT using models as “evidence” or “data”, but as foil. Saying “Look, the data does not agree with the model. The model is wrong. What does that mean?”
I can not praise this paper enough for the clear way the authors follow the Scientific Method. Please read it, the whole thing.
What it finds is that the actual history of recorded eclipses in India from 400 A.D. to 1800 A.D. does not match what a NASA model post-dicts for them. They then look at that difference and discover that the lunar “orbit” of the Earth must change more than predicted and that the tides on the Earth must be strong enough to change the Length Of Day. Think about that. LOD is dependent on the Moon and the particular orbital status. That is a LOT of mass to move around. Even at milliseconds, it is a big effect. Certainly more than it takes to move some air around on the surface and change some temperatures…
That is how Science is really supposed to be done. When the model diverges from reality, the model is WRONG. What can we learn from that wrongness?
Some quotes (that do not do justice to the article. Please do read it.):
Ancient eclipses and long-term drifts in the Earth–Moon system
M. N. Vahia1,*, Saurabh Singh2, Amit Seta3 and B. V. Subbarayappa4
1Tata Institute of Fundamental Research, Mumbai 400 005, India
2Department of Electronics Engineering, Indian School of Mines, Dhanbad, Jharkhand 826 004, India
3Centre for Excellence in Basic Science, University of Mumbai, Vidhyanagari Campus, Mumbai 400 098, India
4No. 31, Padmanabha Residency, BSK III Stage, Bangalore 560 085, India
We study anomalies in the Earth–Moon system using ancient eclipse data. We identify nine groups of anomalous eclipses between AD 400 and 1800 recorded in parts of India that should have completely missed the subcontinent according to NASA simulations (Es-penak, F. and Meeus, J., NASA/TP 2006–214141, 2011). We show that the typical correction in lunar location required to reconcile the anomalous eclipses is relatively small and consistent with the fluctuations in the length of day that are observed in recent periods. We then study how the change in the moment of inertia of the Earth due to differential acceleration of land and water can account for this discrepancy. We show that 80% of these discrepancies occur when the Moon is at a declination greater than 10 and closer to its major standstill of 28 while it spends 46% of the time in this region. We simulate the differential interaction of the Moon’s gravity with land mass and water using finite element method to account for land mass and water mass. We show that the results of eclipse error are consistent with the estimate of a small differential acceleration when the Moon is over land at high latitudes. However, we encounter some examples where the results from simulation studies cannot explain the phenomenon. Hence we propose that the T corrections have to be coupled with some other mechanism, possibly a small vertical oscillation in the Moon’s rotational plane with period of the order of a few hundred years to achieve the required adjustment in eclipse maps.
The system is made more complex by the fact that the temperature fluctuations over a year have changed the mass distribution on Earth. Hence small fluctuations in the length of day are not fully amenable to an analytical solution even with more than 120 terms. However, the fluctuations are minor and not fully exposed by short-period studies of a few decades. To understand the nature of interaction, it is important to have long-period data. Based on individual eclipse records it has been shown that the drift time T that characterizes long-term drift in the Earth–Moon system is not as smooth as conventionally thought (see refs 12–15 for a survey of the field). Here we use a database of more than 500 solar eclipses record-ed in India between AD 400 and 1800 to quantify the drift in the location of the Moon with time.
Now we see the value of long term preservation of original observations. Unadorned and unadulterated by “value added”. Simply put, it takes a very long baseline data set that has NOT been corrupted, adjusted, or changed in any way to do real Climate Science. In this case, 1200 years of carefully recorded data. If the “errors” in the data had been “adjusted” away, nothing would be learned. Had the models been held more accurate than 1000 year old observations, nothing would be learned.
Subbarayappa and Vahia have made a catalogue of more than a thousand eclipses recorded in the subcontinent from AD 400 to 1800. A small study of this nature was done by Shaylaja. In the present study we compare the ancient Indian records of solar eclipses from AD 400 to AD 1500 (see also ref. 18). We find more than 500 solar eclipses in this period. Out of these, 114 are mentioned in more than one record. We then compare these observations with eclipse predictions by Espenak19 (http://eclipse.gsfc.nasa.gov/eclipse.html). We find that 15 of these eclipses have paths that did not pass over the region at all where the observations are recorded. We then study single observations of eclipses around these periods and we show that there is a general trend of several close by eclipses whose paths also do not fall as expected. In order to determine the time interval of anomalous eclipses, we assume that an eclipse is anomalous if the disc coverage at the location of observation is less than 20%, as predicted by Espenak19. We extend the period on either side of the observations till we come across two consecutive eclipses where the expected and observed paths agree. We find nine distinct periods when eclipses around these multiple observations also have paths which do not pass through the point of observation. We label them as anomalous eclipse periods. These lie in the range given in Table 1.
This anomaly may be caused by subtle differences in the Moon’s location compared to the values used in the NASA calculations. We then study the location of the Moon during these anomalous periods and find that it is significantly closer to major standstill during this period. We then calculate the differential acceleration of the Earth due to its varying oblateness because of the fact that water mass has a much greater displacement compared to land mass due to lunar gravity. We show that this difference in moment of inertia of the Earth is consistent with fluctuations in the length of day and the errors in location of the Moon derived from our calculations. This is consistent with the fluctuations observed in East Asian records and the fluctuations in length of day recorded since the advent of atomic clocks.
In short: The model is wrong. The data are right. It shows changes in lunar orbit change the tides, the distribution of water on the planet, and through that the Length Of Day. (Along with the shape of the Earth).
There is an interesting graph of the change in the moment of inertia with the declination of the Moon. Another of L.O.D. variation with lunar declination. Then trend in L.O.D. over time. And more. It explains a fair amount. For example:
Though the change is small, under extreme conditions (e.g. high declination of the Moon, perigee), it can cause slight perturbation in orbital velocity that can result in shift of the shadow during eclipses either in latitudes or longitudes (depending on the exact geometry of the situation). There are certain cases possible where the Moon can either slow down or speed up as a result of the above interaction and hence can shift the shadows of Moon on Earth in a dramatic manner.
The Earth L.O.D. can change. The Moon can either slow down or speed up. Water sloshes all over. Think that makes a difference to air temperatures? Of particular interest is this snippet:
As can be seen from these figures, the discrepancy in the observation of eclipses arises primarily when the Moon is closer to one of the standstills.
In computer programming, two very common errors are “off by one” and “edge cases”. That change of behaviour near Standstill is an example of an “edge case”. I would speculate that the effect is even larger during Major Standstill and perhaps even much more during a Major Standstill at lunar and Earth perigee. IMHO, it is that which is part (most?) of the mechanism of the 1470 / 1800 year cycles of weather. At edge cases the Moon does something special / more; and we’ve not allowed for that.
The “conclusion” section is also interesting:
We have used data of ancient eclipses recorded in the Indian subcontinent and compared them with the NASA calculations of ancient eclipses. We have identified nine periods of anomalous eclipses consisting of 17 eclipses with multiple observations where the NASA calculations suggest that they should not have been visible in India. We have studied the fluctuations in the Earth–Moon system
based on minor (of the order of 10–8) fluctuations due to the fact that the water mass responds to the Moon with physical displacement of the mass compared to the land mass which does not get displaced. The simulations suggest a small but significant effect of this movement, with the Earth moving faster when the Moon is at standstill. A large fraction of anomalous eclipses in fact occurs when the Moon is close to the standstill. However, fluctuations in the rotation of the Earth cannot satisfy all anomalous eclipses, as the above discussed fluctuations can only result in small drifts in horizontal shifts in eclipse maps ( T corrections). However, for examples where huge spatial and time corrections are required, we need to couple the above-studied phenomenon with another mechanism(s) to account for anomalies. The possible corrections would be to look into changes in Moon’s inclination or fluctuations in its secular acceleration at a long-term scale.
In short, the Moon moves, and that then moves the oceans and the weather. It moves more than we expect (than NASA expects in their computer models) and those changes are greatest near Major Standstill. (This also implies that further changes in Major Standstill from very long term changes of the lunar orbit not considered in the article would have similarly large effects.) The Sun moves the Moon. The Moon moves the tides, water and more. They move the weather and longer term “average weather” that is mistakenly called climate. The Moon changes more than we have observed in recent times (since our lives are very short) and old musty history and old musty un-adjusted data matters. The Ancients knew something about the Major Standstill and that it mattered a great deal. Enough to erect stones to mark it. I suspect they knew exactly what it meant and why it mattered. That is the time when “Things Change”… and not always for the best – warm and mild; but sometimes to the worse – cold and wild.
So that is the mechanism I see that connects the solar changes to the weather on Earth. Sure, there is room to add in changes of Galactic Cosmic Ray (GCR) mediated clouds, shifts of the Jet Stream from zonal to meridional, changes of UV and heat distribution to Stratosphere and deep ocean, and so much more. But the core, IMHO, is the major planets moving the Sun, the Sun moving the Moon vs the Earth in orbit together, then the Sun and Moon shifting tides and the distribution of cold water on Earth (along with our L.O.D.). Those changes of water flow and distribution change the typical air temperatures and humidities over the oceans, and that shifts the weather. “Climate Change” starts in the major planets and the Sun. It gets here via the pedantic changes of the Moon and Tides. “As above, so below”.
Those changes are far larger than folks generally think. Mostly due to our lives being much much shorter than the 1470 to 1800 year basic cycle of the Moon and weather. Partly due to the lunar orbit being a bit more “wild” than we presently think (but attested in historical weather data and eclipse data.)
So look to the Moon. Look at 9, 19, 56, and longer cycles. That is what will grant true insight, and true predictive ability. And at all times remember that the ‘highest and best use’ of computer models is to illustrate where our understanding is wrong. Real Data, even 1600 year old musty real data, is far more valuable than any number of “simulations”. It does not take magic “teleconnections” to explain things. All it takes is to recognize that things are a bit different in a Binary Planetary System and that our partners in space matter.
Some miscellaneous images. Just so folks don’t have to chase a lot of links. First up, a couple from LG in comments
A full circular view:
Then this one I talked about showing the orbit of Luna as a tennis ball on a basket ball court, were the Earth the size of a basket ball. Note that the comments about it says the moon rises up / down out of the plain by about a ‘tennis racket’ of height. That is, the moon goes significantly above and below the actual size of the Earth, since the moon is orbiting about 5+ degrees tilted to the ecliptic (or Earth / Sun orbital plain).
Text from the caption on the Orbit Of The Moon wiki page:
With the Earth scaled to the size of a basketball, the Moon is the size of a tennis ball and orbits at the distance of the 3-point line. And with the court as the ecliptic plane, the Moon’s orbit extends out of that plane by the distance of a tennis racket (10.46 Moon diameters).
That 10+ Luna diameters extension out of the plain of the Earth orbit is an important point. The only thing I can see that constrains the moon from passing over the top of the Earth is the eccentricity limits set by the Luna / Sun orbital mechanics. The Sun dominates the Luna orbit, not the Earth. To me, it looks like we are just depending on Orbital Resonance and the Solar / Earth dynamic to keep things always with a “normal” Luna eccentricity with respect to the Earth. Essentially, since Luna orbits the Sun as the dominant player, not the Earth, how much does the Luna / Earth dynamic of necessity really stay forced into a “moon goes around Earth” dynamic? I don’t know, as I’m not that versed in orbital mechanics and I’ve seen a LOT of crazy orbits looking at what is expected and allowed; so I know I can’t say for sure what it must do.