Why I think that the Earth is Special

The Big Question: Are We Alone?

I anxiously anticipate the discovery of intelligent alien life; what they call Extraterrestrial Biological Entities, or EBE. Some say they've already been here. Some say they're still here. Some say they've met them. Some say that we are the aliens. I find all these possibilities very exciting and a little scary.

Personally, I feel confident that "life as we know it" (liquid water organic chemistry) is ubiquitous in the Universe. Of course, bacteria satisfy the requirement for alien life, but what I really want to see is intelligent alien life.

It's estimated that our Universe contains some 100,000,000,000 galaxies and our galaxy contains some 300,000,000,000 stars. Our Sun is just one of those stars. Our star has planets as do most of those other stars. With all those stars and planets surely the Universe is teaming with life. What could possibly be so special about Earth?

I posit that what makes the Earth special is the Moon.

To understand my assertion, let's take a look at Earth's nearest planetary neighbors, Venus and Mars, as well as the best theory that we have for how the Earth acquired the Moon.

Venus

Venus is often called Earth's twin; or evil twin. Venus and Earth are almost identical in size, density, and composition. In fact, Venus and Earth were so similar when the solar system was young that if their orbits had been swapped, Venus might look like Earth today and vise versa. Despite these early similarities, the differences today could not be more extreme. With an atmospheric pressure 92 times that of Earth and a constant day and night temperature of 863°F, Venus is truly a hellish place and no place for folks like us.

So what went wrong? Is Venus simply too close to the Sun? Perhaps. But, what I find most interesting about Venus is that, unlike Earth, it lacks a magnetic dynamo in it's core, leaving it's atmosphere exposed to the ravages of the solar wind.

Mars

Mars, on the other hand, is smaller than the Earth; much smaller. Mars is half the diameter, less dense, and only 11% the mass of Earth. Despite these differences, it's becoming clear that the early Mars was much more like Earth with an atmosphere, oceans, and a magnetic field driven by a core dynamo.

But today, Mars is a cold, barren wasteland. What went wrong? Besides suffering a glancing blow from a large object that blew off it's north pole region and remodeled 40% of its surface, at some point in time it's magnetic dynamo died. Again, this left the atmosphere exposed to the solar wind which has been stripping it away ever since. There are various theories regarding the demise of Mars' magnetic field, but I feel that it's simply that Mars is just too small to maintain its core heat.

The Moon

If God wanted man to become a spacefaring species, He would have given man a moon.
— attributed to Krafft Ehricke

The theory that best explains available data regarding the origin of the Moon is the Giant Impact Theory, which posits that Earth was hit by a Mars sized object called Theia. Experiments and computer simulations show that the speed and angle of impact are critical for the Moon to form as we see it today. An impact a few degrees more direct would result is much more devastation to the Earth and no moon while a more glancing blow would not result in the formation of the moon. It's this rare "just right" impact that I feel makes Earth special.

Giant Impact Theory simulations show that the Earth gained the iron-nickel core from Theia, which is confirmed by the fact that Earth's density is slightly greater than Venus'. Also, the Moon, with a very small metallic core is only 60% as dense as Earth. In addition to adding to Earth's core, the impact injected heat energy into the Earth late in its development. Both of these factors helps extend the time that Earth can maintain its magnetic dynamo.

In Conclusion...

I believe the Moon's greatest impact are the strong tidal forces it exerts on the Earth. These tidal forces not only cause the ocean tides, but they also "work" the mantle keeping it hot and fluid. This is why I feel that the Earth still supports life at the ripe old age of 4.5 billion years. I wonder how many of the worlds out there are as special as the Earth. How long do most "habitable" planets support life? Are Venus and Mars more typical than the Earth?

What do you think?

reply to post by Galileo400


That's an eye-opening theory, and I plan to look further into it. I always believed there was something special about the Earth/Moon relationship; I was just never sure quite what.

Thanks for bringing this to the forum....

Ex_CT2
reply to post by Galileo400

 

That's an eye-opening theory, and I plan to look further into it. I always believed there was something special about the Earth/Moon relationship; I was just never sure quite what.

Thanks for bringing this to the forum....

Thanks for the compliment. I've been tossing this idea around for years, but I had no one (who would care) to share it with; until now. I'm loving this ATS thing.

So: do you recken all those UFOs are just tourists come to see us and our wonderful special Moon?

What sort of souvenirs should I sell at the stand I'm planning to set up for them?

Galileo400
I believe the Moon's greatest impact are the strong tidal forces it exerts on the Earth. These tidal forces not only cause the ocean tides, but they also "work" the mantle keeping it hot and fluid. This is why I feel that the Earth still supports life at the ripe old age of 4.5 billion years.

This isn't quite correct. Venus, Earth and Mars all have liquid portions of their cores and the presence of the Moon has nothing to do with this in Earth's case. Its gravitational influence is far too small. Melting by tidal heating is something found in systems with a high mass to orbital distance ratio, i.e the Jovian system and moons such as Io. With regards to Earth and our own moon, it's simply too far away and possess too little mass to help keep the core liquid.

Venus' problems all stem from its slow rotational speed (which makes each Venusian day roughly akin to 4 Earth months). To simplify it massively, Venus was most likely hit by something rather large in the distant past slowing its rotation down, which in turn shut off mantle convection, in addition to movement in the outer core (and thus the dynamo), leaving the volatile elements in the atmosphere prone to atmospheric stripping by the solar wind. Without these volatiles (especially water), any conventional tectonics on the planet also would have ground to a halt and the this led to the emergence of the major resurfacing events every 600 million years or so as the dominant factor in determining the planet's atmospheric composition.

A moon wouldn't have saved it from its current fate. In fact there are even theories that an ancient Venusian moon could have been the initial cause of the whole problem!

NoExpert

This isn't quite correct. Venus, Earth and Mars all have liquid portions of their cores...

I never said that Venus and Mars had solid cores. I said that their dynamos were not working...as in no convection. (I didn't actually say the no convection part, but that's why.)

NoExpert
With regards to Earth and our own moon, it's simply too far away and possess too little mass to help keep the core liquid.

Again, I never said that either. I said "mantle", not "core". It is my theory that by keeping this top layer of the mantle moving it helps remove heat which helps maintain a steady convection which is critical to maintaining a working dynamo and possibly preventing major crustal upheavals which would be devastating to life on Earth.

I do not have proof nor did I say that the presence of the Moon is in fact the reason why the Earth has maintained a life friendly environment here on Earth. I presented facts (correct any errors, please) and then presented my theory, posit, belief, etc. about the Moon.

Except for the two above misquotes, everything you said is spot on. You really know your planets. I'm aware of all these facts that you have added, I just didn't want to write a 400 page dissertation on the planets. I admit, I picked the facts that support my case, we all do that. Now, are there any statements that I presented as fact that are wrong? I welcome your input as you seem to know your stuff.

Respectfully, Galileo400.

Our solar system is very special. Have you ever seen the chaos in a jointed pendulam? Well our solar system has at least 9 joints in its pendulum. I just can not fathom how our solar system keeps in relative balance over billions of years.

Galileo400
I never said that Venus and Mars had solid cores. I said that their dynamos were not working...as in no convection. (I didn't actually say the no convection part, but that's why.)

My apologies, I did not intend for that to come across as asserting you had said as much, I had merely hoped to use the examples of Mars and Venus both having liquid portions of their cores and mantle (at least geologically 'fluid' anyway) as a way to demonstrate my disagreement with:

These tidal forces not only cause the ocean tides, but they also "work" the mantle keeping it hot and fluid.

Galileo400
Again, I never said that either. I said "mantle", not "core". It is my theory that by keeping this top layer of the mantle moving it helps remove heat which helps maintain a steady convection which is critical to maintaining a working dynamo and possibly preventing major crustal upheavals which would be devastating to life on Earth.

An error on my behalf, I had meant to say mantle. The perils of not re-reading your own posts more than once.

You are quite right to point out the absolute necessity of heat loss from the mantle in order to avoid massive volcanic catastrophes that would certainly spell the end of all life on Earth. However the dynamo has nothing to do with the mantle (if I'm understanding you correctly), its generation lies entirely within the outer core where the convection of liquid iron induces the magnetic field.

By the way may I just add that it's rather good we finally have a more 'general' discussion thread about the planets. Makes a change from all those 'is it a rock or not' threads that usually take up a large percentage of the space discussion on this site.

NoExpert
However the dynamo has nothing to do with the mantle (if I'm understanding you correctly), its generation lies entirely within the outer core where the convection of liquid iron induces the magnetic field.

Actually, it does. It is true that the liquid iron-nickel core (or outer core) is where the magnetic field is generated. But, in order for it to work the fluid must be moving relative to the planet as a whole. In order to get this outer core moving there must be convection, which is heat flow by way of a moving fluid. The mantle (liquid rock) expresses heat out through the crust, cooling the outer mantle and therefore making it denser. The mantle material near the outer core is heated by the core and therefore making it less dense. Then, gravity will move the cooler denser magma down and the hotter less dense magma up. Thus, we have mantle convection.

Now that the mantle is moving heat out of the planet, this cools the outer layer of the outer core while the inner layer is heated by the inner core. Thus, in the same way, we have outer core convection and a working dynamo. If the mantle is insulated too much, the convection will stop and the dynamo will die. This may be, in some way or other, what happened to Venus and Mars.

My theory is that the Moon keeps the Earth's outer most layer (crust and outer most mantle) broken up and moving so that heat can escape at a fairly steady rate; kind of like when you crack the lid on a boiling pot so it doesn't erupt on you. Perhaps, without the Moon, the crust would completely solidify (like the pot with the lid all the way on) and lead to catastrophic crustal turn over which would vent huge amounts of heat. Then, the crust would solidify much deeper and stronger and insulate the mantle, killing the dynamo, and there goes the atmosphere; according to my overactive imagination.

It seems rare that anyone mentions the fact that our moon is huge, compared to the size of other planets/their moon(s). And if viewed from the surface of Earth, the moon is the exact same size as the sun (the moon's disc perfectly fits the sun's during an eclipse). Artificial moon?

Kaiyuss
...And if viewed from the surface of Earth, the moon is the exact same size as the sun (the moon's disc perfectly fits the sun's during an eclipse). Artificial moon?

I don't believe that our moon is artificial. Actually, some solar eclipses are total and some are annular; meaning that there is a small ring, or annuls, of the Sun showing around the Moon. This difference is because the Moon's orbit around the Earth is not a perfect circle.

Also, it is believed by many in the science communitiy that the Moon began it's life MUCH closer to the Earth and is slowly moving away into larger and larger orbits. So, I think we just got lucky that in our epoch that the Moon and Sun's apparent size is so close.

A double pendulum.

A triple pendulum

reply to post by Galileo400


I agree the moon is the major factor the earth is unique.

But you accurately show the possibilities out their. There will be other factors that make other planets equally as unique. There will be planets with moon, and some with several moons. The point is it is just not possible that there is not other intelligent life out there.

I think we will find out soon i just hope it is not too late. I have had the feeling of something coming welling up in me for a while now. Something is coming, my whole body is vibrating with it. I just wish I knew what It was lol.

I am leaning towards the grids going down but this is only from strange info from friend who works for utility company.

The Bot

Like I was saying about our moon...

thespacereporter.com...

a reply to: Kaiyuss

If you raise your thumb into the sun and adjust it's distance to the eye you are using to look at it, it also covers the sun.

Artificial thumb?

Perhaps an advanced race "nudged" the Moon to a "sweet spot" to provide the tidal forces we have today?

A type II or III civilization could do something like that ...