The Earth has the distinction of being the third planet from the Sun, but may be better known as the only planet ever discovered that supports life on its surface. Scientists date the planet’s age at around four and a half billion years old, and the formation resulted from the same solar nebula that collapsed and allowed the creation of our Sun. At that time our beloved planet would have been almost entirely molten, and it may have taken as much as twenty million years for water to form on the surface and cool it into a solid mass. The first signs of life began to crop up about a billion years after the Earth’s formation, and the greatest mystery of the universe is why our planet accomplished this feat when thousands of other studied planets have not.
While this question may never be fully answered within our lifetimes; the answer, or some form of it, must lie within the Earth itself. Of the countless planets that have been studied by satellites and telescopes throughout the history of our civilizations, our planet is the only known location of water in liquid form. While it exists as a gaseous vapor or solid ice in comets, meteors, and other planets, the relative location of the Earth from the Sun is what has allowed water to become present and initialize the presence for millions of individual life forms that have inhabited our planet since its creation.
Our ozone layer and Earth’s magnetic field are also responsible for much of our survival, since combined they effectively block out over 91% of the Sun’s ultraviolet rays and help deter serious collisions with our planet. These factors were not present when the Earth was initially formed since evidence exists that an object the size of Mars collided with our planet, and the debris from the glancing blow almost was eventually what led to the formation of our moon. Since the moon’s presence also provides stimuli for hundreds of thousands of organisms within our oceans and on land, it may actually fit somewhere within the equation of our origins.
Another unique feature of the Earth is our tectonic plates, which are massive solid structures that rest atop our planet’s mantle. Guided by the convection that occurs deep beneath the surface, tectonic plates move freely across the globe and renew the Earth’s surface with their steady movement. They are thought to have formed most of the mountainous regions above and below sea level and could in fact hold clues as to the presence of our oceans and their salinity.
While there are still countless mysteries regarding the Earth’s formation and how we fit in to the universe, scientists almost unanimously agree that the majority of the answers reside right here within our planet. If other intelligent species truly inhabit the landscapes of distant planets beyond our atmosphere, then there must be some common denominator to explain it. By studying the Earth and understanding why we are here may in fact someday provide that very answer.