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The Cosmos and the Development of Life

Updated on January 14, 2015


What I present here is the "accepted" theories about the formation of the solar system and Earth, by way of the scientific community. It is not my intention to disregard or diminish in any way the other theories on the subject, including the Creator theory. As always, I'm happy to discuss those theories further in the comment section, or perhaps in another hub entirely.

X-Ray image of a supernova remnant, captured by Kepler.
X-Ray image of a supernova remnant, captured by Kepler. | Source

Exothermic vs. Endothermic Reactions in Stars

As elements are fused in stars, they logically increase in mass. This increase makes the continued fusion process more and more energy-consumptive, and this energy is what prevents the collapse that causes a supernova. These earlier reactions are considered exothermic, because more energy is created than is used in the reaction. Once the Iron-56 is formed, the energy cost of fusing the particles is greater than the energy produced in the reaction. These are endothermic reactions, because they absorb heat rather than produce it.

Supernova: We are stardust

You health nuts out there, name a few of the nutrients in foods and supplements that we need to live. I'll wait.

Iron is the big one, and not just for nutritional purposes. All of the iron in the Earth, whether it's in your multivitamin or your frying pan, was created in the heart of a star. A good chunk of the periodic table owes it's existence to the nuclear fusion that powers the sun and it's brethren across the universe, in fact.

Starting with hydrogen, a star is powered by fusing atoms together. When the two particles are fused, the result is the creation of helium and a bit of lost matter in the form of energy, which powers the star. When the hydrogen supply runs short, the helium is then fused with hydrogen or other helium to form lithium and beryllium. The beryllium atoms in turn can be used as part of the triple-alpha process to form carbon. This is a good time to remember that we are carbon-based lifeforms, by the way.

This process continues, fusing heavier and heavier elements and allowing the star to continue to burn. However, the moment iron is formed, the star is in it's death throes. Iron is the last element which produces a positive return of energy when fused, so every subsequent reaction causes the star to lose energy, and as the fuel is gradually converted to a non-fusible element the resultant energy production is reduced until the core begins to collapse, creating conditions that allow for carbon fusion, leading to the production of iron. The end result of this process is a star which can no longer produce enough energy to maintain equilibrium with it's own gravitational force, the outer layers of the star collapse. When this shell reaches the core, a shockwave results and sufficient temperatures and pressures are reached to create even heavier elements in the subsequent explosion.

Depiction of the modern solar system
Depiction of the modern solar system | Source

What Happened to Mars?

Formation of the Solar System

Our little solar system is estimated to be about 4.6 billion years old, born when matter in a large molecular cloud collapsed under the force of gravity. Most of that matter coalesced in the the center to form our sun, and the remainder began to swirl around and flatten into a proto-planetary disc. Within this disc, planets, moons, asteroids, and most of what resides in the borders of the system formed by accretion, which is to say that they began as dust and, through collision, gradually into larger and larger objects. As these objects orbited the newly-created sun, they continued to collide and rebound, gradually forming larger planetary bodies and their satellites.

The temperatures in the inner solar system were too high for low melting-point molecules to condense, so the only available elements for the formation of the inner planets were silicates and metals. These terrestrial planets, since they were composed of rarer elements, could not grow to the sizes we see in the gas giants beyond Mars which are made up of lighter and more common elements.

Gradually, the remnants of the molecular dust that filled the solar system was collected by the forming bodies or blown away by the solar wind, forming the outermost planets and bodies that orbit our star and casting the remainder into interstellar space.

Composition of the Earth's Crust

Other elements exist in the crust in smaller quantities. Heavier elements like iron and nickel sink into the mantle and core.
Artist depiction of the Theia Collision event.
Artist depiction of the Theia Collision event. | Source

How the Moon Formed: The Theia Collision

The current leading hypothesis on the formation of our moon is that sometime about 4.5 billion years ago a large object collided with Earth. During the period a large number of planetary bodies would have formed, which would have included not only the planets we know today but many more. One such body has been named Theia, after the Greek Titan and mother of the Moon Goddess Selene.

Though it is theorized that such collisions happened frequently in the early history of Earth, this one is special in it's conditions. Theia is thought to have been roughly the size of Mars, about 1/3 the size of Earth, and to have struck the infant planet off-center. The result was that most of Theia was absorbed by the larger Earth, but the remnants of the collision scattered into orbit and accreted into what we know today as the Moon.

This collision may also be responsible for the tilt in the Earths axis. This tilt results in seasons, which are considered to be one of the many essential ingredients for life. Additional effects of having our Moon are tidal pull and orbital stability, both of which are critical in the formation of life as we know it today.

The Late Heavy Bombardment

During this period, it is thought that a large number of objects were drawn in from the asteroid belts by orbital shift in the gas giants, hurling these bodies into the inner solar system causing a massive number of collisions that would have brought additional and more varied materials to the earth. This theory is evidenced by a large number of dated impact craters on the other terrestrial planets and remnants of such on Earth.

It is interesting to note that the beginnings of life on Earth are dated to just after the end of this period, roughly 3.8 billion years ago. This fact has lead to a controversial theory that life on Earth was carried here from space, though this hypothesis is not widely accepted in the scientific community.

The Earth as seen from Apollo 17
The Earth as seen from Apollo 17

Author's Note:

The series of events that lead to the world we live in is full of pure luck. Were it not for these examples and scores of others, life would not exist as we know it, and I think it's worth taking a moment to acknowledge the amazingly unlikely confluence of coincidences that resulted in the existence of life that is capable of contemplating it's own nature.

However far we advance as a society and seek to master our environment, we are a product of luck on an inconceivable scale, and that, I believe, is something we should all be grateful for.

I hope you enjoyed reading, and as always feel free to track me down on Facebook, or visit my home page for more information on the many, many things that made the world what it is today.


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    • Nadine May profile image

      Nadine May 

      4 years ago from Cape Town, Western Cape, South Africa

      This is indeed an well written article on this topic. The way you have theorized that a collision was responsible for the birth of our Moon and that this collision could be responsible for the tilt to our axis is also something to ponder over. I'm still very drawn to the idea ( not a belief) that our ancestors were seeded ( or rather genetically modified) from elsewhere.

    • Glenn Stok profile image

      Glenn Stok 

      5 years ago from Long Island, NY

      I have always found our universe a very mystical phenomena. There are so many coincidences that brought about the existence of everything, including life. I found your discussion extremely interesting. Even though I have studied the formation of our solar system and our galaxy, I never lack the desire to learn more. And I enjoy your well-written and informative way of describing this subject.

    • JG11Bravo profile imageAUTHOR


      5 years ago

      Thank you, I'm glad you enjoyed it! It really is a fascinating subject.

    • annajazz profile image

      Anna Marie 

      5 years ago from New Mexico

      Fascinating and informative Hub. It is really interesting to ponder the though that we are each made up of molecules the are so old and where once part of something else. The fact that it is theorized that the collision that is responsible for our Moon could also be responsible for the tilt to our axis is fascinating. To think that each of these events led to our existence, makes for really good brain candy to ponder on.


    • JG11Bravo profile imageAUTHOR


      5 years ago

      Well thank you for your insight, and as always I'm glad you enjoyed yourself!

    • Faith Reaper profile image

      Faith Reaper 

      5 years ago from southern USA

      Excellent article here. For all the very reasons you state in your article, it seems to me to not be pure luck, and as you state in your author's note, "life would not exist as we know it" ...exactly ... what are the odds of everything fitting so precisely together, seems to me to lean towards a Creator. I am so glad that science is now confirming and lining up more so ... One of the most amazing discoveries in physics over the last half century is that the universe is so finely tuned that it rules out the possibility of its creation being a coincidence. The numbers that govern the universe just barely allow life to exist.

      The cosmological constant is the energy density of space. If it were too positive, the universe would fly apart. If it were too negative, the universe would implode.

      The strong nuclear force that binds together the nucleus of an atom, if decreased by a tiny fraction of an amount, would cause the universe to have only hydrogen, making life impossible since it requires oxygen.

      If the number of electrons and protons didn’t equal each other, galaxies, stars and planets would not be able to exist.

      I am just offering my thoughts here, as you have too. You have a very high intellect, especially in science, and so I cannot even go there. Although, I have read a lot and came up with such as I have stated here.

      Again, interesting article, and thank you for sharing your thoughts.

      Blessings, Faith Reaper

    • JG11Bravo profile imageAUTHOR


      5 years ago

      See, folks? Civil discourse is possible, even when religion is involved.

    • lone77star profile image

      Rod Martin Jr 

      5 years ago from Cebu, Philippines

      JG, thanks for your delightful response. And no apology necessary. Say "hello" to your delightful puppy.

    • JG11Bravo profile imageAUTHOR


      5 years ago

      On the subject of meteor impacts, I believe that they were undoubtedly a factor in the formation of the planet. Those objects would've carried materials that would have otherwise been non-present or present in reduced quantities by way of natural formation via the accretion hypothesis.

      As for the Creator theory, specifically that God was the "architect" of the conditions that I list in this hub, I can't prove or disprove it. All I can say on the subject is that it has been proven that it is not necessary for a higher power to have had a hand in creating the universe. Of course, that doesn't mean that it did not happen. To close my mind to any possibility wouldn't be a very scientific approach, after all.

      P.S. I apologize for posting in two comments. My puppy has mastered the art of dropping toys on my keyboard to get my attention, and that makes lengthy posts a bit taxing.

    • JG11Bravo profile imageAUTHOR


      5 years ago

      Sir, thank you. Sincerely. This is exactly the kind of intelligent, insightful discourse that I hope to bring about with this sort of hub.

      That being said, you are correct. There are alternate theories for nearly everything I've written here, honestly, but I did my best to stick to the "accepted" versions among the scientific community at large, if nothing else for the sake of practicality. If I had explored numerous theories here, I'd be sitting on 20,000 words or so.

      Still, you're right, and perhaps a minor amendment is in order to acknowledge some of the other possibilities out there.

    • lone77star profile image

      Rod Martin Jr 

      5 years ago from Cebu, Philippines

      JG, beautifully written and nice facts. I enjoyed it.

      But you jump to one unfounded conclusion. While it's possible that everything that happened to Earth to make it habitable was "accidental," that has by no means been proven. If it was purely accidental, then we might see fewer Earth-like worlds in the universe and more space between them. Perhaps two or three per Milky Way-sized galaxy, instead of thousands?

      One experiment in California several years ago proved that meteoric collision can add complexity to molecules! If you catch the implication, here, you might see that life could have occurred when it did because the prior bombardment had "stirred the soup" of chemical complexity to the right degree.

      The thesis that life was seeded from elsewhere seems a bit thin, because it merely passes the buck. How did life get started, if the only way for life to get started on a world is to have it come from elsewhere? Oops! (Infinite loop, as we computer scientists like to call it. Reiterative half-solution which never quite makes it.)

      And, of course, there is the other solution that some scientists are finding not "politically correct" -- God did it. As a scientist, I'm quite all right if God didn't have a direct hand in the sequence of events in Earth's history or the spark that started life. But some scientists have an obvious bias against the idea that God exists. I find any bias in science sad. Things like the "Clovis First" dogma are some of the dark spots of history -- science by ridicule or unsupported dismissiveness.

      Of course, bias is not restricted to science alone. Anyone with an ego can be biased. I find too many of the religious caught up in their own biased interpretation of the Bible. They diss anything in science that gives an ancient age of things and try their best to twist facts to make their theory fit. Painful to watch.

      Any discovery takes humility and a hunger for answers. As children, we have this in abundance. A rare few never lose this. Some learn how to reclaim it. Change is only scary if you live by vulnerable ego. Changing your mind about the meaning of things, even several times, is an essential part of personal growth and learning.

      I have studied both science and religion for over half a century. They have a lot in common, though they each deal with different realms. Science deals with the products of creation, while religion and spirituality deal with the sources of creation. In every way, they are complementary.

    • JG11Bravo profile imageAUTHOR


      5 years ago

      No, I didn't know that actually. See? I learned something too.

    • josters profile image

      Janik D 

      5 years ago from Dresden, Germany

      Very good article, well composed and informative. Did you know that the picture of the earth you used at the end was originally taken "upside down" and rotated by NASA to apply it to our maps and the way we've seen earth so far? This is actually very interesting because an upside down map like this is equally true.


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