Is Earth's Distance from the Sun the Key to Life on Our Planet?

[nickwetz]

I have, through general observation, theorized what I believe to be a logical explanation for the appearance of life on Earth. Although to me, this theory seems to provide a logical and rational explanation for the question of how life appeared on Earth, I have very little knowledge of Physics, and must assume that due to the shear simplicity of the model, this has not only been postulated before, but is indeed incorrect and contains a myriad of fallacious assumptions about physics, astronomy, cosmology etc. That being said, the sole purpose of this post is to learn what, specifically, is problematic, incorrect or impossible about what, to me is a very obvious explanation to the question being asked. So, as simply as possible, this is what I have concluded. Several components are required to allow for the possibility of life. First, an energy source, in our case the sun. Second, an environment with the required chemical composition to allow for a "primordial soup" scenario, given an energy source is provided. With what little knowledge of the Nebular Theory I do have, it is my understanding that the creation of the planets (in our solar system for the purposes of this discussion) was the result of a myriad of events, ultimately resulting in the collision of particles from the solar nebula which formed the planets in our solar system. Assuming that this theory is correct, it would then be logical to assume that (at least at one point in time), all of the planets in our solar system have very similar compositions, as they were formed from the same material. That being said, one could also conclude that because we know life is possible on Earth, it is also possible on the other planets of our solar system. So now the question of why Earth, and only Earth. Obviously there are an endless number of differences and variations between Earth and the other planets of our solar system (size, atmosphere, gravitational pull, climate etc.) that could account (solely of jointly) for the lack of "life facilitating" conditions on the other planets in our solar system, however in my mind, only one difference ultimately serves as the determining factor. That difference, is distance from the sun. Essentially what I'm saying, is that the Earth is exactly the necessary distance from the sun to facilitate life. Obviously this would presuppose a few things. First, that this "life zone" or the portion of space which is located exactly the right distance from the sun to facilitate life, is equal to or greater than the dimensions of the Earth (otherwise, portions of the Earth would fall outside of this zone and be incapable of sustaining life). Next, this zone must not be greater than the current distance from Mars to Venus, otherwise life would co-exist on one or both of those planets (currently), as well as on Earth. Assuming that life on Earth has existed for approximately 3-4 billion years, and the sun is approximately 4 billion years old, this theory also presupposes that the growth of the sun thus far has not been sufficient enough to "push" the Earth out of the life zone. Because of the similarities between Earth and Mars, logic would seem to point to the boundaries of this zone falling close to the space Mars occupies. Eventually, as the sun continues to age and enlarge, Earth will near the inner-most boundary, and Mars will near the outer. As this process continues, the environment of Mars will begin to resemble Earth, and the conditions necessary for a "primordial soup" would exist. If the sun had an infinite life-span, and continued to expand, every planet in our solar system would produce life during the time which they occupied this zone.

This is an extreme over-simplification of my observations, as well as pretty much every theory, construct and idea I've described within it. This is in large part due to my own ignorance on the topics, and in small part due to my desire to stop typing ASAP. What I'm interested in learning most here is the following: What's the most glaring problem with this theory? Has this theory been considered or examined in any form before? Would the other planets in our solar system, if placed in the exact location of the Earth, have Earth-like features, environments, atmospheres, chemical compositions etc? Again, I apologize in advance for the juvenile and ignorant nature of this post... Feel free to voice your disgust and contempt for me after reading this.

 

[DaveC426913]

(at least at one point in time), all of the planets in our solar system have very similar compositions, as they were formed from the same material.

Yes. At one point in time. But subsequently, the inner, rocky planets followed a very different path from the outer gaseous planets.

That being said, one could also conclude that because we know life is possible on Earth, it is also possible on the other planets of our solar system.

No. See above.

So now the question of why Earth, and only Earth. Obviously there are an endless number of differences and variations between Earth and the other planets of our solar system (size, atmosphere, gravitational pull, climate etc.) that could account (solely of jointly) for the lack of "life facilitating" conditions on the other planets in our solar system, however in my mind, only one difference ultimately serves as the determining factor. That difference, is distance from the sun. Essentially what I'm saying, is that the Earth is exactly the necessary distance from the sun to facilitate life. Obviously this would presuppose a few things. First, that this "life zone" or the portion of space which is located exactly the right distance from the sun to facilitate life, is equal to or greater than the dimensions of the Earth (otherwise, portions of the Earth would fall outside of this zone and be incapable of sustaining life). Next, this zone must not be greater than the current distance from Mars to Venus, otherwise life would co-exist on one or both of those planets (currently), as well as on Earth. Assuming that life on Earth has existed for approximately 3-4 billion years, and the sun is approximately 4 billion years old, this theory also presupposes that the growth of the sun thus far has not been sufficient enough to "push" the Earth out of the life zone. Because of the similarities between Earth and Mars, logic would seem to point to the boundaries of this zone falling close to the space Mars occupies. Eventually, as the sun continues to age and enlarge, Earth will near the inner-most boundary, and Mars will near the outer. As this process continues, the environment of Mars will begin to resemble Earth, and the conditions necessary for a "primordial soup" would exist. If the sun had an infinite life-span, and continued to expand, every planet in our solar system would produce life during the time which they occupied this zone.

The zone you're looking for is indeed distance from the sun (actually more generally: energy available**), but coupled with atmospheric pressure. The key is the conditions for liquid water. Read up on The Goldilocks Zone.

There are only a few bodies in the solar system that have a solid surface AND a temp in the right zone for liquid water AND an atmosphere thick enough to keep the water liquid. Only one of them is a planet. (**There are several moons that might support life but they are not proximal to the sun. Instead they are energized by the huge gravity of their gaseous parent planets.)




Your thoughts describe what place(s) might be habitable for life, yet they do nothing to illuminate your opening premise, which is how or why it did so:

...a logical explanation for the appearance of life on Earth. Although to me, this theory seems to provide a logical and rational explanation for the question of how life appeared on Earth...

 

[DevilsAvocado]

...
What's the most glaring problem with this theory? Has this theory been considered or examined in any form before? Would the other planets in our solar system, if placed in the exact location of the Earth, have Earth-like features, environments, atmospheres, chemical compositions etc?
...

I think DaveC426913 answered your questions most thoroughly.

The most important factors for Earth (alone) providing interesting forums like PF are:

• Mercury, Venus, Earth & Mars are solid rocky planets.
• Jupiter, Saturn, Uranus & Neptune are gas giants.
• Mercury & Venus are way too hot (427°C & 461°C).
• The best candidate is Mars who used to have liquid water and a dense atmosphere, and http://marsrover.nasa.gov/home/index.html" are looking for traces of life right now...

One important factor for life on Earth is the 'rotating' iron core, creating a magnetic shield against lethal radiation from the Sun. Furthermore, some say this field (magnetosphere) also protects the atmosphere from being tear down by the solar wind. Mars lack this magnetosphere and one theory is that this explains why Mars lost its denser atmosphere.

Another very interesting fact about the magnetosphere is that it eliminates most radiation from the Sun, but not all. The radiation that gets thru is thought of as very important factor for the evolution of life since it creates 'rapid' random mutations in the genes (some very dangerous and some 'useful'), and thus have helped to speed up the evolution of life!

I’m not sure what you mean when talking about "the growth of the sun"...? When the Sun gets closer to its death it will blow up to a Red Giant (approx. in 5 billion yrs), but then it’s way too late to start a new evolution somewhere else. The living 'creatures' that has not left the solar system by then will die a terrible death...

Personally I believe the http://en.wikipedia.org/wiki/Extrasolar_planet" will someday (in the near future?) show signs of life. There are 424 such planets known to this date, and the numbers grows quickly...

 

[DaveC426913]

Another very interesting fact about the magnetosphere is that it eliminates most radiation from the Sun, but not all. The radiation that gets thru is thought of as very important factor for the evolution of life since it creates 'rapid' random mutations in the genes (some very dangerous and some 'useful'), and thus have helped to speed up the evolution of life!

Excellent point. There are myriad contributing factors to life on Earth.


Awesome username, btw.

 

[DevilsAvocado]

...
Awesome username, btw.

Thanks! I like your 'rakish brain'.

 

[Chronos]

It is doubtful the unique factors contributing to life on Earth are very unique in a galaxy containing ~200 billion stars - in a universe containing billions of galaxies. It is more sobering to consider how difficult it may truly be to traverse the distance between stars.