My #FridayFlash and The Big Splash

My #FridayFlash this week ("The Planet That God Built") refers to the "Big Splash", an event 4,500,000,000 years ago when an object the size of Mars smashed into the the early Earth. The horrific impact ripped both planets apart and set them spinning as a cloud of ejecta. A huge mass of material coalesced to become the Moon, with the rest becoming the Earth. Mostly, the lighter stuff went to the former, while the denser stuff went to the latter.

The kinetic energy imparted to the nickel-iron core of the Earth and the spin from the impact are what gives us the active molten core we have today. That, in turn, gives us the magnetic field that shields us from the solar wind. Without it, the ions from the sun would crack our water up, causing the hydrogen to float away. We'd be utterly dried out, like Mars and Venus.

No impact = no spinning core = no magnetic field = no protection = no water = no life.

As an added bonus, having such a large moon (~3% of the Earth's mass) in such close proximity spin-stabilized our rotation, with lots of excess torque being transferred to the lighter body. The Moon's rotation got locked with its orbital period and our rotation and processional period slowed. That keeps us from getting baked and frozen with a too-long or too-short day.

AND the relatively low concentration of light silicates on Earth (since we gave most of that light stuff to the Moon) means we have a thin crust. That gives us slow, churning plate tectonics with large swaths of the crust perfectly intact and stable. Every billion years or so, Venus undergoes a single massive upthrust, wherein the entire surface is consumed and sunk under the lava. This happens because its crust is much thicker than ours. But here on Earth, it's just the edges of the plates that erode; the bulk of the crust is stable long enough to let life evolve and thrive.

Funny how it all worked out from such an unlikely coincidence. A planetoid of JUST the size hitting us at JUST the right time and at JUST the right angle to give JUST the right spin and JUST the right distribution of densities, elements and conditions to allow life to evolve. That's quite a coincidence... if it was a coincidence.

||| Comments are welcome |||
Help keep the words flowing.

No comments:

Post a Comment

Thank you for leaving a comment. The staff at Landless will treat it with the same care that we would bestow on a newly hatched chick. By the way, no pressure or anything, but have you ever considered subscribing to Landless via RSS?