This trilogy was a Christmas gift by friend, scientist and freethinker Terry Loucks, co-author of "Burning Words: A Book About the Gospel of Gospels". It shows that the Earth itself is a true Christmas miracle. I'm facilitating its publication to interested readers because of its sheer excellence.

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Our Rare Earth

In the beginning, namely the Big Bang, conditions were so violent that only simple atoms like hydrogen and later helium survived. So where did all the other elements come from?

The simple answer is that they were "cooked up" by stars much larger than ours, stars that then exploded and spread their products into the cosmos. These exploding stars are called supernovas.

http://en.wikipedia.org/wiki/Supernova

Our own star, the Sun, and its planets happily were formed from supernova dust that was rich in heavy elements. Some star and planet systems, especially in earlier universe times, were not so fortunate, and their Periodic Tables had many gaps.

http://www.webelements.com/

http://www.ptable.com/

Additionally, had we come along sooner in the universe, both quasars and supernova explosions would have been hazardous and sterilized our Earth. Had we come later, the probability of having plate tectonics would have decreased dramatically. As we shall discuss later, plate tectonics have been vital to the sustained temperatures on Earth over billions of years.

http://en.wikipedia.org/wiki/Plate_tectonics

Continuing, it turns out that our spiral galaxy is a perfect shape. Elliptical galaxies often do not have enough heavy elements. Neither do globular clusters, which also have hot and colliding stars.

Our galaxy is also a perfect size, since smaller ones often lack the heavy elements.

Our Sun has a perfect location in our galaxy. In the center there would be too many collisions. On the edges there are frequently not enough heavy elements.

The large planets in our solar system fortunately did not spiral into the Sun or outer space, taking Earth with them, as is often the case. In fact, the planets, including Earth, all have relatively stable orbits.

Additionally, our sister planet, Jupiter, runs interference for us by clearing out many comets and asteroids.

Our Sun is the right size to last a long time, which is great for evolving complex life. At 5 billion years, our Sun is halfway through its life.

Earth is the right distance from the Sun, basking in the rather narrow habitable zone. Mars and Venus, although reasonably close to us, did not fare so well.

Earth has the liquid water needed for life near the surface and the oceans are just the right size, not too large and not too small. Larger oceans would have covered the land provided for complex evolution while smaller oceans would not have allowed ocean circulation belts to average global temperatures and salinity.

Earth has a large moon, thanks to a freak collision of Earth with an object the size of Mars. Had it hit Earth directly, both bodies would have shattered. If it had hit at a more glancing angle there would be either no moon or a much smaller one.

The Moon, which happens to be the right distance away, stabilizes Earth's tilt and creates the tides that nurture life in marshes and estuaries. A near perfect tilt has kept the seasons from being too severe.

Earth is far enough from the Sun to avoid locking the Moon's tides.

Earth is the right mass so that its gravity retains the atmosphere and oceans but does not flatten living organisms. If it were much stronger, only crickets would survive.

Earth has a solid/molten core that provides enough heat for plate tectonics, as the elevated landmasses essentially "float." The benefits of this are explained later.

Earth has a carbonate-silicate cycle that holds its temperature in bounds. (Keep in mind that normal temperature cycles for millions of years have swung from lengthy ice ages to brief interglacial periods like the present, which is somewhat extended.) The geochemistry of this cycle is a little complex and can be found at the following website.

http://www.geosc.psu.edu/~kasting/PersonalPage/ResInt2.htm

Basically, it is a weathering process, which slows when Earth's temperature drops, causes carbon dioxide, a greenhouse gas, to build up in the atmosphere. What amazes me about these chemical equations is that they use the same oxygen, carbon, hydrogen and calcium that appear in our bodies.

The solid/molten core, made mostly of iron, also creates a magnetic field that protects us from the Sun's output of dangerous charged particles. Mars, in comparison, does not have this because the core is no longer molten.

http://www.blurtit.com/q884994.html

http://en.wikipedia.org/wiki/Earth%27s_magnetic_field

Our "floating" continents and landmasses have enhanced biotic diversity, leading to conscious life like us.

Earth's atmosphere, in part due to microscopic photo synthesizers in the oceans, has had ideal temperature, composition, and pressure for plants and animals. In particular, it has had just the right amount of oxygen, which evolved at a propitious time.

In spite of many giant impacts in Earth's early life, there have been no completely sterilizing impacts for at least 500 million years since the Cambrian era.

http://en.wikipedia.org/wiki/Cambrian_explosion

Nevertheless, there have been five major extinctions that wiped out much of life since the Cambrian era. Humans and their lowly ancestors, from sea worms to shrews, miraculously survived them all.

Our Sun will last another 5 billion years, as mentioned above, but because the Sun is gradually getting both larger and hotter, Earth will only be habitable another 500 million years. It turns out that we are right in the middle of the window for life here, since life has already been evolving for about 500 million years since the Cambrian era.

The atmosphere, mostly nitrogen and oxygen, just happens to offer a window to the Sun's visible light. Photo synthesizers like algae and leaves have evolved to take advantage of this.

Every element in the Periodic Table deserves a gold medal, because they combine in so many different ways that are fortuitous for us. But water is worthy of honorable mention. It is the cradle and sustainer of carbon life, and it holds this distinction because it is "polar" and essentially a universal solvent.

http://ga.water.usgs.gov/edu/waterproperties.html

It is made of two elements, hydrogen and oxygen, which show up in many other places including our DNA. In the solid form, ice uniquely expands and floats rather than sinking to the bottom of lakes. Water also stabilizes temperatures on Earth by taking up and giving off lots of heat during phase changes.

Amazingly, this is the same hydrogen that "burns" in a nuclear sense in all the stars including our Sun.

click here

Our planet, as we know, has a "complete" Periodic Table of the chemical elements. In particular, it has enough carbon for life as we know it to have evolved, but not enough for a runaway greenhouse effect.

Putting all these together, Earth has provided a rare evolutionary pathway for complex plants and animals.

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis

Authors Website: www.Ioncehadafarminireland.blogspot.com

Authors Bio:
Ursula Siebert, originally a German teacher & lecturer turned businesswoman, lived in different European countries before coming to the USA. She is now a free-lance writer. Often tongue-in-cheek, she sees life and politics in the USA from the perspective of a European blow-in.