Since long before the birth of humankind, the moon has been the Earth’s constant companion.
But until relatively recently we’ve known little about its true nature.
Strong Backer 坚强后盾
During this early period of its life, the moon had its most profound effects on Earth. The 1)massive collision that created the moon was so powerful that it knocked the Earth off balance, onto an axis of 23.5 degrees. It’s this tilt that gives us our spring, summer, autumn and winter. If we spun on a vertical axis—like the planet 2)Mercury, seasons wouldn’t exist.
But the moon did more than merely produce this tilt—it also maintains it. The strong 3)gravitational pull of our moon acts as a global 4)gyroscope stabilizing the Earth’s axis. Without our “Global Stabilizer,” our axis could vary between 0 and 90 degrees. This would alter the distribution of sunlight across the surface of the planet, devastating our finely balanced weather systems. Climate patterns would go 5)berserk. The tropics could find themselves frozen under ice, and Antarctica would be transformed into a vast desert. But luckily, the moon saves us from such disasters and allows life to exist.
Disaster Reliever 挺身而出
When we look at our moon today, the first things we tend to notice are the 6)craters. Most of these craters came from 7)meteorites hitting the moon. The largest crater we can see from our planet is the 8)Imbrium Basin, which is 1,100 kilometers across. Moon craters come in various sizes but almost all were created at about the same time.
Around four billion years ago, a chance 9) alignment of the gas giants Jupiter and Saturn changed the shapes of their orbits. This created a 10)slingshot effect—hurling 11)asteroids towards the inner solar system, straight at Earth and its young moon.
And the Earth’s gravity made it worse—pulling meteorites and asteroids directly towards it. On its own, the tiny moon might have escaped with less damage, but it was too close to the Earth. So, asteroids heading for impact with Earth, hit the moon instead.
The moon became the first victim of 12)collateral damage.
The Ultimate Force 终极力量
Three billion years ago, the moon was too far away to have a dramatic effect on the rocks of the Earth, but the moon did affect the oceans. As the moon passed overhead, its gravity created tides in the water. But these weren’t like the tides of today. They were hundreds of meters high.
Neil Comins (Astronomer): They probably would have covered hundreds of miles and then they would come back 13)scouring the land, taking debris from the surface of the Earth into the oceans.
The material sucked into the seas contained minerals and nutrients. And the tides created by the moon churned these into the most crucial cocktail in the history of the Earth—the 14)Primordial Soup. Different combinations of minerals were bound together, and torn apart. And it was in this violent melting pot that the right combination of minerals was forged into life.
The power of the nearby moon has dramatically reshaped our planet. Over the last three billion years, the moon has continued its journey out into space. Its influence has waned, but it hasn’t disappeared.