Astronomy is the oldest science known to man and every time we think about astronomy we think about stars and other galaxies far, far away. Now don't get me wrong, astronomy is the science that studies how the universe works, but you can also learn a lot about other worldly phenomena by understanding how our own planet works and how it was formed.
Planet earth as far as we know is truly unique and special, is the only planet in the universe that we know that is capable of hosting intelligent life and that by itself is a miracle. The earth is not only capable of sustaining life, but also provides enough resources that allow a great variety of life forms to develop and co-exist. It also gives the opportunity to all kinds of organism to flourish; from microscopic entities to complex structured beings such as ourselves. So how exactly and when the earth began? By analyzing the radioactive decay of the most ancient rocks on the planet by a carbon 14 test it can be determine the age of the rocks and how long ago they were formed and hence the age of the earth itself. Carbon 14 tests made on ancient volcanic rocks all around the world dictates that the earth is about 4.5 billion years old, which is very close to the age of our solar system.
A possible theory that is supported by experts on this matter is that when our sun was forming huge amounts of rocks, gases and iced particles floating around the sun's gravitational field, combined over thousands or even millions of years to form what we now know as the planets of our solar system. These cosmic elements combined like ingredients on a hot stew over millions of years by colliding into each other. Each collision made the chuck of rock gas and icy body bigger and bigger, giving it form, increasing the thermal activity of the body and attracting other chunks of rock that came near it by the gravitational force. This process continued on making the once relatively small chunk of rock gas and ice that didn't have any definite form big enough to actually take a round shape by the force of gravity, and so the blue print for our planet was traced. Just because a celestial body is large enough to be called a planet does not mean in any way that it has the necessary ingredients to sustain life.
For the first billion to billion and a half years the earth was just a molten sphere with raging and violent volcanic eruptions that came deep within the center of the earth. Our earth's center is formed by two types of cores; one is the inner core, a solid sphere made of iron and other elements and the external core which is made out of molten iron and rock. We owe our planet's atmosphere to the constant thermal and dynamical activities of the earth's core. It is believed that the heat that forms from the core is the product of the collisions the earth received when it was formed. The constant geothermal activity from our planet's past till present is the product of radioactive materials decomposing over time still taking place at the earth's center which fuels the earth itself. Scientist all over the world agree that in order to find live on a planet that is similar to ours we must follow the water. One of the theories scientists believe was the reason we have water on earth, is due to the constant bombardment over hundreds of millions of years of frozen asteroids that melted once they entered the atmosphere when the earth was forming.
So now we know what elements need to be present in order to form a planet that applies not just to ours but to other planets on the cosmos. Always keeping an open mind that one day we might find one besides ours.
