Works T H E
OF HIS HANDS
Our Moon: Faithful Witness in the Sky
A
round 3,000 years ago, the ancient people of Israel found themselves leaving Egypt, freed from the bonds of slavery. Their God had devastated the nation that held them captive and was leading them out of that nation to meet Him—to make a covenant with Him and to establish them as His people. As they traveled, a full moon reigned in the sky above—a cosmic witness to the momentous events occurring below. Yet the moon is a witness to more than the events of human history. It also testifies of its Creator—illustrating the special attention He gives to our planet and to the life He has fashioned upon it. A Unique Cosmic Relationship Some scientists estimate that perhaps only one percent of the planets in our universe have natural satellites as substantial as ours. In fact, in our solar system the relationship between the earth and its single moon is unique—an aberration from what we would expect based on our current theories of planet formation and what we see of other planets. The moon is only about one-fourth the size of Earth, yet this is an extremely large ratio compared to other planets and moons—five times the second-place pair (Neptune and its moon Triton). Because our satellite is so relatively hefty, its effects on our planet are significant and observable in everyday life. The most noticeable of these effects may be the tides of our oceans. More than 50 percent of the variation we experience between high tide and low tide is due to the gravitational pull of the moon on Earth’s water.
28 Tomorrow’s World | March-April 2019
The largest tide differences in the world occur at the Bay of Fundy in Canada, where the difference between low tide and high tide can reach more than 50 feet, or 16 meters! The towering cliffs there are a testimony to the power of tides to shape the land along the shore. The erosion of land caused by swinging tides releases life-friendly minerals and nutrients into ocean waters. The pattern of life in our coastal regions is greatly influenced by the cyclical nature of the tides, and engineers are working to devise ways to harness the energy of tidal changes to generate power we can use on land. The constant reshaping of our planet caused by the moon does not stop with our seas. Geologists have learned that even the solid earth moves and bulges in a tide-like fashion in response to the moon’s gravity. While the effect may not seem so noticeable, highly sensitive instruments, such as some particle accelerators, must be designed with these changing “earth tides” in mind. A Stabilizing Hand and Source of Wonder Many scientists believe that our unique moon plays a significant role in stabilizing the earth’s spin on its axis. Relative to our orbit around the sun, the axis of the earth is slightly tilted, about 23.4° from vertical. This tilt causes the cycle of seasons, as energy from the sun strikes the surface of the earth at different angles over the course of the planet’s year-long orbit. However, scientists believe that this tilt would progress to a wild and violent wobble, with dramatic effects on our climate, were it not for the stabilizing
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