GEOSCIENCE REPORTS
Fall 1995, No. 19
Where did the moon come from?
Part II
Wayne Slattery
Los Alamos National Laboratory
Editor's note: In Part I (see Issue #18) the author expressed the idea that the moon could have been created on the fourth day of creation week or it could be older than creation week as it contains no life. Since the Genesis text can be read either way, the author assumed, for the purposes of this study, that the moon was created by God at some time in the past by processes that could be scientifically explored. He developed a computer-generated model to describe one the way the moon could have formed.
The Giant Impact Hypothesis
In a 1985 conference about the origin of the Moon, most of the
attending scientists realized that all of the currently popular ideas (see Part I), along
with other more obscure theories, on the origin of the Moon had serious reasons why they
couldn't work, and the way was opened for a totally new hypothesis to be explored. As you
can guess from the title of this section, the most attractive new hypothesis that they
considered, asserted that a giant object the size of Mars impacted the early Earth and the
debris from this collision formed the Moon. If most of the rocks in the Moon came from the
impactor, then you would nicely account for chemical differences between the Earth and the
Moon. Also the angular momentum of the Earth-Moon system would be exactly the right
amount, since whatever angular momentum went into the collision would be what came out. If
the probability of such collisions is somewhat low then you also nicely account for the
fact that Venus and Mars do not have large satellites. (Mercury is too close to the Sun to
have a large distant, satellite.) As you recall from the earlier discussion on the origin
of the Solar System, it is very natural to have collisions of objects, because the planets
are thought to have accumulated by collisions of rocks; it is just the question of having
the right collision.
As you are aware, it is one thing to have a vague idea of what might
work and another to be reasonably sure that a hypothesis could actually work out
physically (and still another to KNOW that it actually DID happen that way). This is where
my work and the work of my colleagues comes in. Since we couldn't actually experiment with
a proto-Earth and a Mars-sized impactor, we did the next best thing and simulated the
collision in a supercomputer.
To do a collision of a proto-Earth and a Mars sized impactor on a
computer we used a hydrodynamics computer code (or hydro code for short). A hydro code
divides the materials of interest into little pieces and lets each piece interact with its
surroundings according to the laws of physics. The smaller the pieces the better we are at
resolving the problem. However, even current supercomputers are limited, so
the"little pieces" represented about one ten-thousandth of the Earth at our best
resolution. At that time, one of my colleagues was developing a very robust hydro code for
simulating collisions. After testing and correcting the code on various types of
collisions where we knew the answers, we were confident that it could simulate a collision
which we couldn't test in the laboratory.
The model proto-Earth and the impactor both had an iron core and a
dunite mantle. (Dunite is a good average for the rocks of the Earth outside of the core
and we also had an equation-of-state for it [the equation-of-state for a material
represents the relationship between its density, temperature and pressure--for example, a
marshmallow is much softer than a rock--and an equation-of-state would reflect that
difference].) In the type of hydro code that we used the materials were represented by
"particles" which interacted via an equation-of-state and gravity. The
calculation was fully three-dimensional.
After doing a number of computer experiments we found an initial setup
which resulted in a collision which produced a proper sized Moon, which had very little
iron in it. In the figure we show snapshots of the calculation as it progressed. Let's go
through it step by step.
The first figure shows a Mars-sized object approaching the proto-Earth
from the right. The planets are almost touching and the impactor is tidally distorted. The
central dark areas are the iron cores of the planets and the lighter areas are the dunite
mantles. The number in the upper left-hand corner gives the time from the beginning of the
calculation in hours; most of the action occurs in less than 24 hours. The second figure,
at T=0.184hr, shows the initial break up of the impactor. The iron core surges ahead in
the third figure, T=0.758hr, where it forms the bottom central part of the crescent shaped
spread of the impactor. At T=1.122hr, and T=2.344hr, the iron core has collapsed to an
ellipsoidal shape and is heading towards the proto-Earth while the rocks remain in a line
behind. Between the figure 5, where T=2.344hr, and figure 6, where T=4.107hr, the iron
tugs (by gravitational attraction) at the rocks which have been left behind, boosting them
to a higher orbit even as it plunges into the proto-Earth, leaving a tremendous splash in
the figure 7 (T=4.551hr). At times T=9.763hr and T=23.036hr, a proto-Moon, of the right
size, (plus other debris) is seen to be orbiting the Earth.
[DIAGRAMS GO HERE]
Since the iron core of the impactor re-collided with the Earth, the newly formed Moon is very poor in iron, thus satisfying one of the chemical constraints. The other chemical constraints are neatly satisfied because the impacting, Mars-sized object, would have formed elsewhere in the Solar System and therefore be different than the Earth in its rock chemistry. You would also expect this early-Moon to have fewer volatile elements, because of the collisional heating. Physically, the angular momentum of the Moon would be exactly right. The Moon is also closer to the Earth than the present Moon. But this is what we would expect (recall that the Moon is moving away from the Earth now).
Conclusion
Given our current understanding of the origin of the Solar System, the giant impact hypothesis for the origin of the Moon seems to provide a plausible mechanism to explain what the Moon is today. Even though this hypothesis satisfies the physical and chemical constraints that we talked about earlier (plus others), it is quite possible that there is as yet some undiscovered constraint that will change or even eliminate the giant impact hypothesis from consideration. In other words, we haven't proved that the Moon came into our skies in this manner; we have only demonstrated an attractive, plausible mechanism for its origin. More generally, we can say the same thing for any historical science. You can show that something might have happened in a particular way, but unless someone was actually there to watch it happen, you never will know for sure. In any case, the giant impact hypothesis will continue to change as we learn about what we think happened in the processes God may have used in the creation of the Solar System.
For Further Reading
the same list used in Part I
EDITOR'S CORNER
Over the years I have listened to a number of scientific and
theological discussions about the origin of the sun, moon and stars on day 4 as recorded
in Genesis 1. Many questions have been raised: Is God the source of light on day 1? Which
stars were created on day 4: planets in our solar system or the whole universe? Was the
moon already circling the earth but not visible until fusion began in the sun's core? The
questions and concepts are very complex and sometimes confusing. As Christians working in
science, we may struggle with these issues as we search for harmony between scientific
theories and biblical statements about origins.
Henry Schaefer is a quantum chemist at the University of Georgia. He's
been nominated five times for the Nobel Prize so his work is considered significant in the
scientific community. U.S. News & World Report (December 23, 1991) quoted Dr.
Schaefer, "The significance and joy in my science comes in those occasional moments
of discovering something new and saying to myself, So that's how God did it. My goal is to
understand a little corner of God's plan."
I like that. On a day to day basis, the way we do science is no
different from the approach used by the secular scientific community so it is particularly
important to periodically take time to acknowledge God's role in our world and in our
science. This is what Wayne Slattery's paper has done for me. I've had to stop and think
about the creation of the moon. Either God literally created the moon on day 4 or God took
a rocky, lifeless orb that He had created earlier and "made" it the lesser light
on day 4. Wayne's theory gives us a glimpse into the processes that might have occurred if
God used the latter option. Either way, Genesis 1:14 clearly says, "And God said, Let
there be lights in the expanse of the sky to separate the day from the night, and let them
serve as signs to mark seasons and days and years, ..."
SCATTERED NOTES FROM THE SCIENTIFIC LITERATURE
ASTRONOMY
Freedman, W., Madore, B., Mould, J., Hill, R., Ferrarese, L., Kennicutt, Jr., R., Saha, A., Stetson, P., Graham, J., Ford, H., Hoessel, J., Huchra, J., Hughes, S., Illingworth, G., 1994. Distance to the Virgo cluster galaxy M100 from Hubble Space Telescope observations of Cepheids. Nature (October 27) 371:757-762.
Using the Hubble Space Telescope the authors measured the distance to the Virgo cluster in an effort to calculate with greater accuracy the Hubble constant. (Astronomers measure the speed at which a cluster is receding and divide that value by the distance to the cluster to determine the Hubble constant relative to the expansion speed.) They calculated the Hubble constant at 80 ± 17. This means that as galaxies move through space the rate at which they are receding from us increases by 80 kilometers per second at increments of 3.26 million-light years (a megaparsec). By extrapolating the positions of the galaxies backward in time, the authors estimated the age of the universe as 8 to 12 billion years. Other astronomers have estimated ages for some of the stars at 14 to 20 billion years. It is difficult to have a universe younger than the stars it contains. The authors comment, "This age conflict suggests that either the standard cosmological model needs to be revised, or present theories (or observations) bearing on stellar and galactic evolution may need to be re-examined." [A more readable version of this paper was included in a more comprehensive article titled "Crisis in the Cosmos" by Sam Flamsteed and published in "Discover" (March) 1995, pages 66-77.]
GEOLOGY
Coe, R.S., Prévot, M., and Camps, P., 1995. New evidence for extraorginarily rapid change of the geomagnetic field during a reversal. Nature (20 April) 374:687-692.
The D41 lava flow at Steens Mountain, Oregon, has been recognized since 1969 as the best record of a geomagnetic polarity reversal. The estimated cooling time for the D41 flow (based on experimental observations in Hawaii) is 8 days and that represents a shift of 10o per day in the magnetic field direction. An earlier study was unable to rule out viscous contamination as a cause for the change in field direction. The authors suggest that the polarity transitions requiring thousands of years may be punctuated by rapid field change events that originate in the outermost core. It is interesting to note that even though external forces could account for the rapid field changes, such forces have been eliminated from consideration because they "cannot easily account for the relatively long-standing pre- and post-jump directions." Once again the assumption (that the process requires long periods of time) wins inspite of direct field observations.
MICROBIOLOGY
Grossman, D. and Shulman, S., 1995. The Biosphere Below. Earth (June):34-40.
Over the past few years drilling projects across the U.S. have recovered more than 8,000 samples of living microorganisms. These samples are coming from rock nearly 2 miles below the earth's surface. The occurrence of live bacteria at depth were first reported by petroleum geologists in the 1960's. Biologists were skeptical of the claims. Many scientists asserted that microorganisms could not live in deep rock so the samples must be contaminated by surface organisms. Frank Wobber, head of the U.S. Department of Energy's Subsurface Science Program, instituted rigorous procedures for isolating the material from possible contaminants. Much research is yet to be done on the samples but new species and even new genera have been found. Currently, microbiologists are trying to determine whether or not the surface bacteria are genetically related to the deep-earth bacteria. Tests are also being conducted to determine whether the surface microorganisms migrated down or the deep-rock varieties migrated to the surface at some time in the past. Are they preserved as "microfossils" after they die?
[Photo of living cyanobacteria]
PALEONTOLOGY
Sergeev, V.N., Knoll, A.H., and Grotzinger, J.P., 1995. Paleobiology of the Mesoproterozoic Billyakh Group, Anabar uplift, northern Siberia. Journal of Paleontology Memoir 39:1-37.
Thirty-three species assigned to 17 genera of well-preserved microfossils were collected from Precambrian rock (shales and cherts) with an estimated age of 1.45 to 1.5 billion years. The fossils are silicified. Spherical, elongated filaments, pill-shaped and colonial structures are described. It is assumed by the geologic community that these microfossils should be assigned the same age as that determined for the associated rocks. However, the existence of live bacteria found at depth today suggests that live bacteria can migrate into rocks of any age. If such recent bacteria are subsequently fossilized, the conclusions that have been drawn in regard to the existence of Precambrian microfossils could be invalid.
[Photo of fossil cyanobacteria]
WE HAVE A NEW DIRECTOR
October, 1994, Dr. L. Jim Gibson assumed the directorship of
Geoscience Research Institute. This July marks Jim's eleventh year with GRI. He is no
stranger to the day to day demands of this job.
Jim attended Pacific Union College acquiring his B.S. and M.S. in
biology. He entered the work force as a biology, chemistry and algebra teacher at
Bakersfield Adventist Academy and also taught biology and chemistry at Rio Lindo Adventist
Academy. Later, Jim and his wife, Dottie, accepted a call to Sierra Leone, Africa, where
Jim taught biology and mathematics for four years. Jim received his doctorate in biology
from Loma Linda University in 1984.
Jim researches patterns of mammal distributions (biogeography) in
Australia. He's developing a computer database as he maps out the distributions. He hopes
to apply this approach to fossil distributions. Jim is also interested in chromosome
evolution, speciation and evolution of vertebrates. He has published 27 papers for the
church (Origins, Dialogue, Geoscience Reports, Ministry, and Christ in the Classroom). In
June of 1992 Jim presented his research at the 72nd meeting of the American Society of
Mammalogists in Salt Lake City, Utah. He holds memberships in five professional
organizations: American Society of Mammalogists, Society for the Study of Evolution,
Society for Systematic Zoology, Willi Hennig Society and Society for Sigma Xi.
We know Jim as a man of genuine commitment to God's Word. He walks up
to the medical center and eats lunch with his wife. He works hard to stay abreast of the
biological and paleontological literature. Jim's very logical and well organized in his
approach to science and writing. He loves birds and "Far Side" jokes. The staff
wishes him every success as our new director.
GRI: A LOOK AT THE FUTURE
Jim Gibson
The question of our origin is an important one. Our understanding of
who we are and the way we relate to other people is heavily influenced by our view of our
origin. In turn, our view of our origin is heavily influenced by our understanding of the
relationship of God, man and nature. Thus, the attempt to find harmony between Scripture
and nature plays an important role in developing one's personal philosophy and
relationship to God.
The Geoscience Research Institute has been established for the purpose
of developing a better understanding of the underlying harmony between nature and
Scripture. The impact of personal philosophy on our understanding of ourselves and our
relationship to God underscores the importance of the work of GRI. The breadth of scope of
the issues presents a formidable challenge to our ability to accomplish our goals. The
high stakes in the issues involved justify our existence and demand our best efforts.
A diversity of activities are involved in the work of GRI, including
gathering data, interpreting data, and communicating with others. We must seek a practical
balance among these activities. We are optimistic about the possibility of acquiring new
facilities, which will increase our efficiency. We plan to establish an electronic card
catalog for our library, with the capability of topical literature searches. We will
maintain our research grant program, and expand it when possible. We look forward to
opportunities for creative discussion in improving our understanding of earth history in a
biblical context. We are examining possibilities for increasing our avenues of
communication. Turly the work in challenging, but we see a bright future for GRI as God
directs and blesses our efforts.
[Photo of Jim somewhere on this page]
ROTH RETIRES
Ariel Roth came to the United States from Geneva, Switzerland. He
completed his undergraduate training at Pacific Union College and did his graduate work at
the University of Michigan. He completed his doctorate in zoology in 1955. Ariel has
taught biology at Pacific Union College, Andrews University and Loma Linda University. He
has also served as Biology Department Chairman at both universities. He first became
associated with GRI in 1971 and assumed the directorship in 1980. Ariel and his wife,
Lenore, have two sons.
Ariel has been actively involved in research throughout his career. He
studies began in radiation biology and animal metabolism switching focus to coral reefs
and turbidites. He has published 23 professional papers on his research over the years and
over 100 papers for various publications within the SDA Church. He is currently writing a
manuscript addressing the issues most relevant to science and religion.
At the last GRI board meeting, the incoming director gave a formal
tribute to Ariel. The following are excerpts from that address: "His dedication to
his work has been exemplary. His stamina has seemed unbounded.... His commitment to
excellence has inspired us all. ... provided visionary leadership ... started
... Origins ... establish[ed] two branch offices ... produc[ed] the
"Flood video"... led BRISCO.... He has always emphasized thorough work, accuracy
in detail, and mastery of the subject ... a strong foundation for the work has been
laid."
We are grateful for Ariel's past leadership and are pleased that Ariel
can continue to work with us. We wish him great success with his long awaited, highly
anticipated and much needed book.
SOME THOUGHTS ON MY WORK FOR GEOSCIENCE
Ariel A. Roth
Working for the Geoscience Research Institute has been stimulating,
and extremely rewarding. I have very much enjoyed the challenge, and the opportunity to
contribute to a significant area of investigation. This area is particularly significant
as it directly impinges on one's world view.
There are not very many areas where you can affect individuals' world
views more than in the area of origins. This affects our whole outlook about our past, our
purpose and our destiny.
Through the years, my study of science has strengthened my confidence
in the truthfulness of the Bible. Not all my questions are answered, but the evidence of
the need of a Designer, and the evidence of a recent creation are more compelling to me
now than they were many years ago.
Probably what I have enjoyed most over the years is taking people out
to many parts of the world and showing them in the geologic layers evidences of rapid
action and a brief time for their deposition as would be expected from the Biblical
account of beginnings.
Evolution is in serious scientific trouble; after 200 years of
intensive search for an evolutionary mechanism, a plausible model seems more elusive than
ever. Likewise, the new trend in geologic interpretations towards catastrophic
interpretations is providing significant support for a recent creation.
The more important part of the work of the Geoscience Research
Institute is not the vindication of God's Word, it is the support this lends to the
knowledge of a kind and loving God. This knowledge is much needed at this time in Earth's
history.
[Photo of Ariel centered on this page]
GEOSCIENCE REPORTS
Fall 1995, No. 19
Editor --- M. Elaine Kennedy
Associate Editor --- Katherine Ching
Subscription requests, correspondence, and notices of change of address should be sent to: Geoscience Reports, Geoscience Research Institute, Loma Linda University, Loma Linda, CA 92350.
Geoscience Reports is a newsletter published by the Geoscience Research Institute to present current happenings at the Institute as well as articles of general interest which deal with creation/evolution issues for secondary-school and college science classes. The views expressed are those of the authors and not necessarily those of the Institute.