EARTH + THEIA = MOON?
“And God made the two great lights – the greater light (Sun) to rule the day and the lesser light (Moon) to rule the night. And God set them in the expanse of the heavens to give light on the Earth.” (Genesis 1:16,17)
For those who want a ‘simple’ explanation, the Bible provides you all you need to know: God made the Moon and he set it in place. If you are curious as to how and why God did it, a planetary astronomer could provide you with more details than you’d care to know. But for most of us, Moon-gazing is a pleasant pastime that summons thoughts of romance and awe of God’s creation.
HOW? There are several theories. The most prominent theory is the collision of a Mars-sized planetesimal (large asteroid) with a molten, still-forming, proto-earth. In the words of not-yet-fallen Lucifer in Countdown to Adam: “So let me get this straight. You (God) are asking me to shoot (with the cosmic cue stick you handed me), this cue-ball-like asteroid named Theia, toward the proto-earth. But won’t the resulting collision cause the complete destruction of both Theia and Earth?...So Lucifer, enlisting the help of two of his trusty angelic assistants, Lys and Valiant, took aim and shot Theia toward proto-earth. At first it seemed to be a mis-fire, a mis-cue, since Theia was traveling toward proto-earth at the snail’s pace of only two miles per second. To complicate matters, Theia appeared to be a little off-course and would only glance off the proto-earth at a 45-degree angle.” But God’s response was: “Great shot, Lucifer!”
Many scientists agree with this scenario; they have evidence that the Moon formed following a collision with Earth by the pre-Moon, Theia, just a few million years after Earth began to form. As a result, Earth and Moon share some crustal chemical similarities, and, of course, the Moon is captured in Earth’s gravitational field as it traverses in orbit. In the beginning, the Moon was only 14,000 miles distant from Earth; the gravitational pull upon Earth was so great that daily tides are estimated to have exceeded 3000 feet (ocean tides today are in the four-foot range)! The Moon is gradually drifting away from Earth at a rate of 1.6 inches per year; it is currently 241,000 miles distant.
Interesting facts:
- We never see the “dark” side of the Moon; tidal forces have locked the Moon into a situation where the same side always faces Earth. The “man-in-the-Moon” never changes.
- After impact, the smaller Moon became solid much sooner than Earth. Heat from the nearby still-molten Earth caused the ‘near’ side to cool much slower than the ‘far’ side; the result is the Moon’s crust on its far-side is much thicker than the near-side.
- The Earth has the largest moon of all the planets, relative to its size.
- The density of the Moon is nearly half that of Earth; that’s because Earth has a dense iron core while the Moon does not.
WHY? When God does something, it is always with purpose, things, like the Moon, don’t just ‘happen’. God planned the Earth as a place to manifest life. No Moon, likely no life. Why might that be?
Earth’s giant plates are constantly in motion; they are driven by huge convection cells from deep within. These cells are fueled by radiation from decaying minerals and by tidal forces from the Sun and Moon. Plate tectonics are known to be a key factor in sustaining life on Earth. Tidal flow helps transfer heat from the equator to the poles, which, in turn, provides favorable climate to support life and diverse speciation of plants and animals. Otherwise, our planet would be a frozen “ice ball”. Early strong tides on Earth are thought to have promoted the development of nucleic acids, precursors to DNA and proteins, the stuff of life. The drag from Moon’s gravity pull over the years has slowed Earth’s rotation from a 6-hour day to its present 24-hour day and has stabilized Earth’s “axial wobble” from 10 degrees to a mild 1 degree. Without these benefits, our climate would be a pressure cooker (800 degrees) like Venus and a wind-storm (300 mph) like Mars. When Theia collided with Earth, its iron core became blended with Earth’s iron core. The result of this iron core is the powerful magnetic field (geo-dynamo) that protects Earth from lethal bombardment of cosmic radiation from the Sun and nearby stars. Life could not exist without this geo-magnetic shield.
So be sure to thank God for the Moon; it’s there just for you!
