The origin, size, and location of our Moon play a unique and essential role for the existence of life on Earth.
Origin of the moon
Encounter with Theia
According to the giant impact theory, near the end of its growth, Earth was struck by a Mars-sized object that came from somewhere between the orbits of Venus and Mars. Scientists call this rogue body Theia after the Greek goddess who was the mother of the Moon. Theia struck the young Earth at a glancing angle. Much of Theia’s bulk came to a halt and merged with Earth. Theia’s iron core plummeted through Earth’s mantle and soon coalesced with Earth’s existing core. At the same time, the part of Theia’s mantle farthest from Earth was sheared off by the collision and continued on its way. This material, under the influence of Earth’s gravity, soon changed direction and went into orbit, where powerful tidal forces ripped it into small pieces. In a matter of hours, Earth swallowed up four-fifths of Theia’s bulk, while the remaining fraction formed a close-orbiting disk of debris. 12
On Dec. 13, 1972, Apollo 17 astronaut Harrison Schmitt walked up to a boulder in the moon’s Sea of Serenity. “This boulder’s got its own little track, right up the hill,” he called to his commander, Eugene Cernan, pointing out the mark the boulder left when it rolled down a mountainside. Cernan bounded over to collect some samples. 11
“Think how it would have been if you were standing there before that boulder came by,” Cernan mused. “I’d rather not think about it,” Schmitt said.
The astronauts chiseled bits of the moon from the boulder. Then, using a rake, Schmitt scraped the powdery surface, lifting a rock later named troctolite 76536 off the regolith and into history.
That rock, and its boulder brethren, would go on to tell a story of how the entire moon came to be. In this creation tale, inscribed in countless textbooks and science-museum exhibits over the past four decades, the moon was forged in a calamitous collision between an embryonic Earth and a rocky world the size of Mars. This other world was named Theia, for the Greek goddess who gave birth to Selene, the moon. Theia clobbered Earth so hard and so fast that the worlds both melted. Eventually, leftover debris from Theia cooled and solidified into the silvery companion we have today. But modern measurements of troctolite 76536, and other rocks from the moon and Mars, have cast doubt on this story. In the past five years, a bombardment of studies has exposed a problem: The canonical giant impact hypothesis rests on assumptions that do not match the evidence. If Theia hit Earth and later formed the moon, the moon should be made of Theia-type material. But the moon does not look like Theia — or like Mars, for that matter. Down to its atoms, it looks almost exactly like Earth.
Confronted with this discrepancy, lunar researchers have sought new ideas for understanding how the moon came to be. The most obvious solution may also be the simplest, though it creates other challenges with understanding the early solar system: Perhaps Theia did form the moon, but Theia was made of material that was almost identical to Earth. The second possibility is that the impact process thoroughly mixed everything, homogenizing disparate clumps and liquids the way pancake batter comes together. This could have taken place in an extraordinarily high-energy impact, or a series of impacts that produced a series of moons that later combined. The third explanation challenges what we know about planets. It’s possible that the Earth and moon we have today underwent strange metamorphoses and wild orbital dances that dramatically changed their rotations and their futures.
To get to the moon we have now, with its size, spin and the rate at which it is receding from Earth, our best computer models say that whatever collided with Earth must have been the size of Mars. Anything bigger or much smaller would produce a system with a much greater angular momentum than we see. A bigger projectile would also throw too much iron into Earth’s orbit, creating a more iron-rich moon than the one we have today.
Early geochemical studies of troctolite 76536 and other rocks bolstered this story. They showed that lunar rocks would have originated in a lunar magma ocean, the likes of which could only be generated by a giant impact. The troctolite would have bobbed in a molten sea like an iceberg floating off Antarctica. On the basis of these physical constraints, scientists have argued that the moon was made from the remnants of Theia. But there is a problem.
Back to the early solar system. As rocky worlds collided and vaporized, their contents mixed, eventually settling into distinct regions. Closer to the sun, where it was hotter, lighter elements would be likelier to heat up and escape, leaving an excess of heavy isotopes (variants of elements with additional neutrons). Farther from the sun, rocks were able to keep more of their water, and lighter isotopes persisted. Because of this, a scientist can examine an object’s isotopic mix to identify where in the solar system it came from, like accented speech giving away a person’s homeland.
These differences are so pronounced that they’re used to classify planets and meteorite types. Mars is so chemically distinct from Earth, for instance, that its meteorites can be identified simply by measuring ratios of three different oxygen isotopes.
In 2001, using advanced mass spectrometry techniques, Swiss researchers remeasured troctolite 76536 and 30 other lunar samples. They found that its oxygen isotopes were indistinguishable from those on Earth. Geochemists have since studied titanium, tungsten, chromium, rubidium, potassium and other obscure metals from Earth and the moon, and everything looks pretty much the same.
This is bad news for Theia. If Mars is so obviously different from Earth, Theia — and thus, the moon — ought to be different, too. If they’re the same, that means the moon must have formed from melted bits of Earth. The Apollo rocks are then in direct conflict with what the physics insist must be true.
“The canonical model is in serious crisis,” said Sarah Stewart, a planetary scientist at the University of California, Davis. “It has not been killed yet, but its current status is that it doesn’t work.”
Scientists struggle to find compelling models of the formation of the moon 3
Scientists have offered several major theories to account for the origin of the Moon. All have drawbacks, but the favored theory that emerged from the Apollo missions was the Giant Impact Hypothesis (sometimes called the Big Splat ). This states that our Moon was created by a collision between Earth and a Mars-sized object some 4.5 billion years ago. There are a number of variations and alternatives, including captured body, fission, formed together (condensation theory), planetesimal collisions (formed from asteroid-like bodies), and collision theories. All of the theories have been challenged, and none satisfy all questions. NASA scientist Dr. Robin Brett sums it up best: “It seems much easier to explain the nonexistence of the Moon than its existence.”
The earth has a huge moon orbiting around it, which scientists now know 1) did not bulge off due to the earth's high rotational speed and 2) could not have been captured by the earth's gravity, due to the moon's large mass. . The best explanation (other Gods supernatural creation described in Genesis) for the moon's existence is that a Mars-sized planet crashed into the earth. The probability of two planets colliding in the same solar system is however extremely remote. Any "normal" collision would not have resulted in the formation of the moon, since the ejecta would not have been thrown far enough from the earth to form the moon. The small planet must have collided with a precise glancing blow in order to account for the angular momentum of the earth-moon system. The collision of the small planet with the earth would have resulted in the ejection of 5 billion cubic miles of the earth's crust and mantle into orbit around the earth. This ring of material, the theory states, would have coalesced to form the moon. In addition, the moon is moving away from the earth (currently at 2 inches per year), as it has been since its creation. If we calculate backwards we discover that the moon must have formed just outside the Roche limit, the point at which an object would be torn apart by the earth's gravity (7,300 miles above the earth's surface). A collision which would have ejected material less than the Roche limit would have formed only rings around the earth. Computer models show that a collision of a small planet with the earth must have been very precise in order for any moon to have been formed at all (coincidence or design?). 7
Paul Lowman, planetary geologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland:
“A lot had to happen very fast. I have trouble grasping that,” he said. “You have to do too much geologically in such a short time after the Earth and the Moon formed. Frankly, I think the origin of the Moon is still an unsolved problem, contrary to what anybody will tell you,”
An article in Nature reports:
We still do not understand in detail how an impact could have produced our Earth and Moon. In the past few years, computer simulations, isotope analyses of rocks and data from lunar missions have raised the possibility of new mechanisms to explain the observed characteristics of the Earth–Moon system. The main challenge is to simultaneously account for the pair's dynamics — in particular, the total angular momentum contained in the Moon's orbit and Earth's 24-hour day — while also reconciling their many compositional similarities and few key differences. The collision of a large impactor with Earth can supply the needed angular momentum, but it also creates a disk of material derived largely from the impactor. If the infalling body had a different composition from Earth, as seems probable given that most objects in the inner Solar System do, then why is the composition of the Moon so similar to the outer portions of our planet? 10
Stabilization of the earth axis tilt through the moon 1
If Earth had no Moon, we wouldn’t be here. First, consider a little-known fact: A large moon stabilizes the rotation axis of its host planet, yielding a more stable, life-friendly climate. Our Moon keeps Earth’s axial tilt, or obliquity—the angle between its rotation axis and an imaginary axis perpendicular to the plane in which it orbits the Sun—from varying over a large range. A larger tilt would cause larger climate fluctuations.At present, Earth tilts 23.5 degrees, and it varies from 22.1 to 24.5 degrees over several thousand years. To stabilize effectively, the Moon’s mass must be a substantial fraction of Earth’s mass. Small bodies like the two potato-shaped moons of Mars, Phobos and Deimos, won’t suffice. If our Moon were as small as these Martian moons, Earth’s tilt would vary not 3 degrees but more than 30 degrees. That might not sound like anything to fuss over, but tell that to someone trying to survive on an Earth with a 60- degree tilt. When the North Pole was leaning sunward through the middle of the summer half of the year, most of the Northern Hemisphere would experience months of perpetually scorching daylight. High northern latitudes would be subjected to searing heat, hot enough to make Death Valley in July feel like a shady spring picnic. Any survivors would suffer viciously cold months of perpetual night during the other half of the year. But it’s not just a large axial tilt that causes problems for life. On Earth, a small tilt might lead to very mild seasons, but it would also prevent the wide distribution of rain so hospitable to surface life. With a 23.5-degree axial tilt, Earth’s wind patterns change throughout the year, bringing seasonal monsoons to areas that would otherwise remain parched. Because of this, most regions receive at least some rain. A planet with little or no tilt would probably have large swaths of arid land.
The Moon’s origin is also an important part of the story of life. At the present time, the most popular scenario for its formation posits a glancing blow to the proto-Earth by a body a few times more massive than Mars. That violent collision may have indirectly aided life. For example, it probably helped form Earth’s iron core by melting the planet and allowing the liquid iron to sink to the center more completely. This, in turn, may have been needed to create a strong planetary magnetic field, a protector of life. In addition, had more iron remained in the crust, it would have taken longer for the atmosphere to be oxygenated, since any iron exposed on the surface would consume the free oxygen in the atmosphere. The collision is also believed to have removed some of Earth’s original crust. If it hadn’t, the thick crust might have prevented plate tectonics, still another essential ingredient for a habitable planet. In short, if Earth had no Moon, we wouldn’t be here. As for the host planet, it needs to be about Earth’s size to maintain plate tectonics, to keep some land above the oceans, and to retain an atmosphere. To maintain a stable planetary tilt, a planet needs a minimum tidal force from a moon. A larger planet would require a larger moon. So indirectly, even the size of Earth itself is relevant to the geometry of the Earth-Sun-Moon system and its contribution to Earth’s habitability. In short, the requirements for complex life on a terrestrial planet strongly overlap the requirements for observing total solar eclipses
Fine-tuning of the moon and its orbit 2
Our Moon is like no other. The ratio of its mass compared to the mass of its host planet is about fifty times greater than the next closest known ratio of moon to host planet mass. Plus, our Moon orbits Earth more closely than any other known large moon orbits its host planet.
Thanks to these unique features, Earth, unlike the other solar system planets, possesses a stable rotation axis tilt, which protects it from rapid and extreme climatic variations that would otherwise rule out advanced life. The Moon also slowed Earth’s rotation rate down to the value at which advanced life could thrive and generated tides that recycle nutrients and waste efficiently.
Only recently have astronomers had any clue how such a special Moon could form. Over the past 15 years, astronomer Robin Canup has developed and improved models that demonstrate that the Moon resulted from a collision between a newly formed Earth (which, at the time, had a pervasive and very deep ocean) and a planet about twice the mass of Mars (Mars = 0.107 Earth masses). This collision took place at an impact angle of about 45 degrees and a very low impact velocity of less than 12 kilometers per second.1 In addition to forming the Moon, this highly fine-tuned event brought about three more changes, each significant for advanced life: (1) it blasted away most of Earth’s water and atmosphere;2 (2) it ejected light element material and delivered heavy elements; and (3) it transformed both the interior and exterior structure of the planet.
In a review article published in a December 2013 issue of Nature, Canup complains, “Current theories on the formation of the Moon owe too much to cosmic coincidences.”3 Indeed, the required “coincidences” continue to pile up. New research reveals that the Moon has a chemical composition similar to that of Earth’s outer portions, a result that Canup’s models cannot explain—unless the total mass of the collider and primordial Earth were four percent larger than the present-day Earth, the ratio of the collider’s mass to the total mass was between 0.40 and 0.45, and a fine-tuned orbital resonance with the Sun removed the just-right amount of angular momentum from the resultant Earth-Moon system.4
Astronomers Matija Ćuk and Sarah Stewart found another way to explain the similar composition. In their model, an impactor about the mass of Mars collides with a fast-spinning (rotation rate = 2.3–2.7 hours) primordial Earth.5 The planet’s fast spin generates a disk of debris made up primarily of Earth’s own mantle material from which the Moon forms, thus accounting for the similar chemical composition. As with Canup’s most recent model, a fine-tuned orbital resonance between the Moon and the Sun is needed.
In an article published in the same issue as Canup’s recent review, Stewart concludes, “In the new giant-impact models, lunar material is derived either from a range of depths in the proto-Earth’s mantle or equally from the entire mantles of two colliding half-Earths.”6 Either way, she adds, that while “each stage of lunar evolution is plausible,” she wonders “with the nested levels of dependency in a multi-stage model, is the probability of the required sequence of events vanishingly small?”7
In her review, Canup suggests that perhaps a small collider (Mars-sized) model can be retained without so much of the added fine-tuning of the Ćuk-Stewart model if the collider’s initial chemical composition were more Earth-like rather than Mars-like. However, extra fine-tuning may be needed to explain this required initial composition.
In yet another article in the same issue of Nature, earth scientist Tim Elliott observes that the complexity and fine-tuning in lunar origin models appears to be accumulating at an exponential rate. The impact on lunar origin researchers, Elliott notes, is that “the sequence of conditions that currently seems necessary in these revised versions of lunar formation have led to philosophical disquiet.”8 What is the cause of this “philosophical disquiet”? May I submit that it stems from the fact that there is now more than sufficient evidence for the supernatural, super-intelligent design of the Earth-Moon system for humanity’s specific benefit?
Tides are vital to life on Earth5
If so, life may ultimately owe its origins to our serendipitously large moon. The sun and wind also drive the ocean's oscillations, but it is the moon's gravitational tug that is responsible for the lion's share of this predictable tidal flux. The moon produces a physical effect over planet Earth, and it is the cause of the rise and fall of the tides. The moon’s gravitational pull exerted over the Earth produces a deformation on our planet, stretching it in those places where the pull is stronger, phenomenon known as “gravity gradient”. Since the Earth’s ground is solid, this pull affects more significantly the oceanic waters, generating a slight movement towards the moon, and also producing a less evident movement in the opposite direction; this is why the ocean’s level rise and fall twice a day. 6
The Moon also assists life by raising Earth’s ocean tides. The tides mix nutrients from the land with the oceans, creating the fecund intertidal zone, where the land is periodically immersed in seawater. (Without the Moon, Earth’s tides would be only about one-third as strong; we would experience only the regular solar tides.) Until very recently, oceanographers thought that all the lunar tidal energy was dissipated in the shallow areas of the oceans. It turns out that about one-third of the tidal energy is spent along rugged areas of the deep ocean floor, and this may be a main driver of ocean currents. These strong ocean currents regulate the climate by circulating enormous amounts of heat. If Earth lacked such lunar tides, Seattle would look more like northern Siberia than the lush, temperate “Emerald City.” If a planet’s moon were farther away, it would need to be bigger than our Moon to generate similar tidal energy and properly stabilize the planet. Since the Moon is already anomalously large compared with Earth, a bigger moon is even less likely. A smaller moon would have to be closer, but then it would probably be less round, creating other problems. 1
24h Rotation rate of the earth through the moon
Another important fact is that, as we all know, our planet rotates completely on its own axis once every 24 hours. But without the presence of the moon and its gravitational effect, the Earth would complete a rotation every 8 hours instead of 24, so one year on Earth would consist of 1095 days of 8 hours each. With a rotational speed as high as this, the winds would be much more powerful and violent than we know today, the atmosphere would have much more oxygen and the planet’s magnetic field would be three times more intense. Under these so different conditions, it is reasonable to assume that if plant and animal life would have developed, it would have evolved completely differently than it actually has. The 24-hour days in the rotation of our planet greatly favors the life forms that inhabit it, since the temperature variations are not too abrupt in the transition from day to night, as they would be in days of only 8 hours. 6 The faster a planet rotates, the faster its winds blow. We see the effects of extreme rotation by looking at Jupiter, which rotates every 10 hours. There, the winds are pulled into east-west flowing patterns, with much less north-south motion than occurs on today's Earth. Furthermore, the wind speeds on Jupiter are typically between 100 and 200 miles per hour. This indicates that the winds on Solon would flow more east-west than they do on Earth and that their speeds would be much higher. Winds of 100 miles per hour would occur daily, and hurricanes would have even higher wind speeds. 8
If ther moon would not exist :
The day would be eight hours long.
The winds would be much stronger.
Complex life might not exist yet.
When life did arrive, it would have a different biology.
- the Moon's distance from the Earth provides tides to keep life thriving in our oceans, and thus, worldwide
- the Moon's mass helps stabilize the Earth's tilt on its axis, which provides for the diversity of alternating seasons
- the Moon's nearly circular orbit (eccentricity ~ 0.05) makes it's influence extraordinarily reliable
- the Moon is 1/400th the size of the Sun, and at 1/400th its distance, enables educational perfect eclipses 4
1. THE PRIVILEGED PLANET Guillermo Gonzalez and Jay W. Richards, page 6
3. Modern Mysteries of the Moon What We Still Don’t Know About Our Lunar Companion, Vincent S. Foster , page 45
12. From Dust to Life The Origin and Evolution of Our Solar System page 179
Further readings :
Yet More Reasons to Thank God for the Moon