Perhaps yes. At least that's the sense I get from reading Jaime Green's
Theia is the heroine of the giant-impact hypothesis concerning the origins of our moon roughly 4.5 billion years ago. To flesh out a timeline (forgive the somewhat strained pun) note that:
In her chapter on Planets, Green writes:
Here are a few excerpts that follow ...
Theia is the heroine of the giant-impact hypothesis concerning the origins of our moon roughly 4.5 billion years ago. To flesh out a timeline (forgive the somewhat strained pun) note that:
Earth is about 4.5 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old. During that 600 million-year window, life may have emerged repeatedly, only to be snuffed out by catastrophic collisions with asteroids and comets. [source]
In her chapter on Planets, Green writes:
But what else makes Earth Earth, beyond the planet's size and distance from its star? Is it our moon, stabilizing our orbit and thus seasons, and whose formation may have thinned the Earth's crust enough to facilitate the plate tectonics that may drive evolution and stabilize the climate by recycling carbon from the atmosphere into the planet's rocks?
Here are a few excerpts that follow ...
- Lots of planets have moons, but ours is decisively larger than most, in proportion to its host planet.
- Our satellite's heft holds the tilt of Earth's axis stable, at the nice 23.5 degrees that gives us the variety of seasons without catastrophic swings.
- The moon gives us out tides, stronger and more variable than they would be from the sun alone. And tides may have shaped evolution on Earth, Rebecca Boyle writes in Scientific American, "shepherding the first plants and tetrapods [four-legged animals] from the salty marshes of the coasts and onto land." The ability to survive in tidal zones, sometimes submerged and sometimes dry, encouraged sea creatures to evolve toward land-dwelling.
- We may also have the moon to thank for plate tectonics. ... With Earth's original, thicker crust, the heat of the mantle wouldn't penetrate, and our planet would ossify and stagnate.
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