Threesology Research Journal
Impact Scenario
The Moon's Origin

(The Study of Threes)

Some readers may be wondering what an Origin of the Moon theory has to do with research into the THREES phenomena. With respect to considerations of what may have been the earliest influence of the "Threes" origin, at least with respect to biological examples such as DNA's triplet codon system (which is actually a 3 to 1 ratio); when the Origin of the Moon is discussed, the speed of the Earth's rotation is a key component. (Unless you prefer to consider that the triplet codon system is of an extraterrestrial origin that "grew up" under the effects of the Earth's environment as it changed.) Hence, while the article below is directly concerned with the formation and evolution of planetary bodies with respect to a collision scenario, the above synopsis bespeaks of a collision between Planetary and Biological Science.

In order to grasp this "Threes Origin Idea", we must engage in a type of thought experiment like that of Einstein: Einstein recalled how, at the age of 16, he imagined chasing after a beam of light and that the thought experiment had played a memorable role in his development of special relativity.

(See for example:) Chasing a Beam of Light

In the present case, the thought "experiment" is rendered thusly: Imagine yourself standing on the Earth so many billions of years ago while the Earth's rotation was considerably faster than the (approx.) 24 hour period of today. The three "moments" of the Sun (dawn- noon- dusk) would have affected the earliest instances of our very sensitive/impressionable biological development (what is sometimes referred to as the Primordial Soup), with a three-patterned stroboscopic irradiation effect. In support of the idea that these three "moments" have an effect on biology, I need only to cite such an example as flowers opening and closing with respect to the hour of the day. Since different flowers are affected by different positions of the Sun, some gardners have made flower clocks that they have used to tell the time. However, we could also cite animal behavior... which includes ourselves and is called circadian rhythms, while other periods of repeated (weekly, monthly, yearly) rhythms can be referred to as ear-marked time-table examples of chronobiology. All of which revolves around the Sun. Necessarily so, as the rate of the Earth's rotation slows, so will the clocks of our biology.

Along with this thought experiment comes the visualization that the path of the daily Sun and Moon do not occur in a linear (across the sky) fashion, nor in a circular-like (arch), but in a triangluar one as the following images reveal:

The following image is of the Moon in eclipse, though the picture could just as easily be a picture of the Sun. I inverted the picture in order to show the complete pathway of ascent and descent. This is a picture taken from page 80 of the 10/97 issue of Natural History magazine showing a time-elapsed image of the Moon during a daily trek but we could also consider a similar image could be offered for the Sun, even though I have not found one as yet. Perhaps someone reading this may know of one, or someone who could provide such, and would send it my way.)

Vboth (19K)

The usage of time-lapsed photography gives us some indication of the environmental conditions early biological life processes were subjected to many billions of years ago when the Earth was spinning faster. Early biological processes would have been subjected to a repeating triangular image for long periods of time in an environment considerably different from today if we can believe what others have written about such times, such as a lessened ozone, volcanic activity, geological activity, precipitation, etc...

Sun and Moon along triangular pathways

The above image was adapted from:

--- University of Massachusetts Sunwheel ---

It should be no wonder that we find this (triangular) image being expressed in a variety of ways by different organisms, within the limitations of their physical/mental ability to do so. If we humans of today can get sun-burned with the current protective ozone levels/layer, it's not too difficult to appreciate how such a triangular image could have been "branded" on the sensitive, impressionable, (highly "suggestable") "hide" of (our) early biological beginnings.

For related comments:

Research into the Threes Phenomena

Source for the Impact scenario image (at top of page):
EMC Community Network

A New Model for the Origin of the Moon

Impact Scenario

Our new model is published in "Making the Moon from a fast-spinning Earth: A giant impact followed by resonant despinning" by M. Ćuk and S. T. Stewart, Science, 2012.

Matija Ćuk and Sarah Stewart propose a new model to explain the remarkably similar chemistry of the Earth and Moon. A giant impact onto a fast-spinning Earth ejects material from Earth into orbit, which forms a Moon that is depleted in iron and has a composition similar to Earth's mantle. After the impact, the rapidly rotating Earth is slowed down by a gravitational interaction between the Sun and the Moon called an orbital resonance.

The leading theory for the origin of the Moon is a giant impact with the young Earth. Recently, the hypothesis has been called into question by measurements that find that the Earth and Moon the same isotopic composition (isotopes of an element have slightly different masses). The isotopes of oxygen and titanium, for example, vary widely in the Solar System and are used to ‘fingerprint’ different planets and meteorite groups. The data show that the Earth and Moon are ‘isotopic twins’, but the original giant impact model predicted that most of the Moon was made from the body that struck Earth, which should have had a different isotopic fingerprint.

Therefore, the original giant impact model has a major problem: it can match the mass of the Moon and the rotation rates of the Earth and Moon, but not the chemistry of the Moon. Today, tides between the Earth and Moon slow Earth’s rotation and push the Moon’s orbit further away, but the total angular momentum (see glossary) is conserved. Going back in time, the early Earth had a day of only 5 hours when the Moon formed. With a post-impact spin period of about 5 hours, a giant impact could not loft enough Earth material into orbit to make the Moon match the chemistry of the Earth.

Ćuk and Stewart show that if Earth’s initial angular momentum were higher, corresponding to an Earth day between 2 and 3 hours, a giant impact can eject enough Earth material into orbit to make a Moon with the same isotopic fingerprint. A day of only 2 hours is near the point when the Earth would begin to fly apart from rotational forces. When the Earth is spinning near this rotation limit, it is much easier to launch Earth material into orbit during a giant impact.

?Furthermore, Ćuk and Stewart found that the early Earth can have a shorter spin period after the giant impact and then later reach the present spin by transfering angular momentum to the Sun through the 'evection' resonance. The evection resonance is a gravitational interaction between Earth’s orbit around the Sun and the Moon’s orbit around Earth. This new work shows for the first time that it is possible for the early Earth to have had a spin period of only 2 to 3 hours after the giant impact. Now, the giant impact followed by an orbital resonance between the Moon and Sun can explain the chemistry of the Moon and the rotation rates of the Earth and Moon.

Earlier scientists speculated about a fast-spinning early Earth. In 1879, George H. Darwin, a son of Charles Darwin who studied tides, suggested that the Moon formed by fission from the Earth (spinning off material from the Earth), but he did not know how to make the early Earth spin so quickly. Modern studies of planet formation show that Earth grew by a series of giant impacts that made the early Earth spin near its rotational stability limit of about 2 hours. The last giant impact formed a Moon that is a twin of the Earth.

The Giant Impact and Moon-Forming Disk

Calculations of the giant impact event model the collision itself and the generation of a stable disk around the Earth over a period of about 24 hours. The methods used for this stage of Moon formation are not able to model directly the formation of the Moon from the disk, a process which occured over 100's of years as the hot disk cooled. A candidate Moon-forming disk is one that has enough mass and angular momentum to make a satellite the mass of the Moon at the Roche radius (about 3 Earth radii, the distance where a satellite is not broken up by tidal forces). The Moon is 1.2% the mass of the Earth and the disk typically has about twice the mass of the Moon.

Example 1:

Movie Link
A Potential Moon-Forming Impact Event

In the animation, Earth and the smaller planet that hit Earth, named Theia, are represented by many particles with a fixed mass, shown as small balls. The color of the ball indicates the material: iron cores and rocky mantles. Before the impact, Earth's shape is an oblate spheroid because the day is only 2.3 hours long.

In this potential Moon-forming impact, Theia has half the mass of Mars and strikes at 20 km/s. Theia penetrates all the way to the core of the Earth and throws material out, temporarily forming a deep hole in the planet. Theia and part of the Earth are vaporized and expand around the planet. Some material is ejected quickly enough to escape the Earth.

The final disk is massive enough to make the Moon and composed primarily of material from Earth (green balls). The disk has almost no iron as the Theia's iron core merges with Earth's core. This impact scenario agrees with the observed the masses of the Earth and Moon, the low iron content of the Moon, and the similar isotopic composition of the Moon and Earth's mantle. After the impact, the Earth has a day of 2.7 hours.

Example 2:

Movie Link
An Unsuccessful Giant Impact

This animation shows the lower hemisphere of the two colliding planets cut through the equator of the Earth. Each planet is represented by many particles with equal masses. The colors show the iron cores and rocky mantles.

In this example, the growing Earth, with a 3.1 hour spin period, is hit by a Mars-mass body at 9 km/s. Because this impact is slower and more oblique compared to the case shown above, a portion of the projectile shears during the initial contact and sends a spiral arm and fragments into orbit around the Earth. Some large fragments impact the Earth and some remain in orbit. The final disk is massive enough to make a satellite as large as the Moon, but about 60% of the disk originated from the impactor's mantle (yellow balls). Thus, this disk is unlikely to make a Moon with the same isotopic signature as Earth.

Example 3:

Movie Link
Orbital Evolution of the Moon and Angular Momentum Loss

A top down view of the Moon's orbit around the Earth, with the Sun's direction fixed to the right. The red line shows the orbit of the Moon as it evolves through Earth tides and the evection resonance.

After the giant impact, the Earth-Moon system had more angular momentum than present day. After the Moon forms from the disk, the Moon's orbit begins to expand outward through tidal forces. The Moon is soon caught in the evection resonance, which fixes the closest point in the lunar orbit to be 90 degrees from the Sun. While the Moon is caught in the resonance, typically for several 10,000 years, the Earth is transferring angular momentum to the Moon via tides. But the Moon cannot absorb the angular momentum while it is caught in the resonance. Instead, the Moon passes the angular momentum to the Sun through the resonance. As a result, the Earth's orbit around the Sun expands slightly. After the Moon breaks out of the resonance, it's orbit continues to migrate outward through normal tides with the Earth. Today, the Moon orbits at about 60 Earth radii. While caught in the evection resonance, the Moon would have appeared almost 20 times larger in the sky during its closest approach to Earth.

A new model for the Origin of the Moon

Your Questions, Comments or Additional Information are welcomed:
Herb O. Buckland