sun position in milky way galaxy

Somewhere between the years 1921-1926, Edwin Hubble, an American astronomer opened the large metal sheet doors to the Mt. Wilson Observatory and beheld the universe.

There he discovered that the clouds of gas swirling in space where in actuality individual galaxies, some much larger than our own. He profoundly changed our understanding of the universe. And gave new understanding to our own galaxy the Milky Way.

That's us right there, within the sunbeam.
Highlighted by a circle. Earth, one small dot.

On September 5th, 1977, Voyager 1 was launched into space. It was to travel to the farthest edge of our galaxy taking numerous pictures along the way. By the request of Carl Sagan an American astronomer, astrophysicist and cosmologist, NASA commanded the Voyager 1 spacecraft, having completed its primary mission and now leaving the Solar System, to turn its camera around and to take a photograph of our solar system across a great expanse of space. On February 14, 1990 now at the edge of our galaxy Voyager 1 turned its cameras around and faced its home.

Thousands of pictures were taken between the months of February to June of 1990 with one picture capturing the hearts and minds of all those who saw it. Taken from nearly 4 billion miles away, a photo of Earth was captured. Surprising even Mr. Sagan, the image of our Earth sat cloaked, surrounded by the darkness of deep space, suspended within a beam of light from our Sun. For some this image struck a chord, begging one to reflect on our creation and raising new questions as to the meaning of our existence. What is our purpose? Are we as a species, a planet, somehow privileged? Is our planetary creation a fluke or an element of creative, intelligent design?

-The mediocrity principle is the notion in philosophy of science that there is nothing special about humans or the Earth. The principle concludes that the Earth is a typical rocky planet in a typical planetary system, located in an unexceptional region of a common galaxy. Hence it is probable that the universe teems with complex life. -Wikipedia

Our planet, how rare are we? Or how common? Without question our planet has won the lottery in terms of conditions and development. Scientists have determined that a chance for planetary creation meeting all the same conditions that we have on Earth equates to 1 in 1,000,000,000,000,000. So how did we get so lucky? There are many factors that lined up just right for our Earth. What are they?

First, our planet is located within the Habitable Zone or otherwise know as the Goldilocks Zone. The habitable zone is the distance from a star where an Earth-like planet can maintain liquid water on its surface and (carbon-based) Earth-like life. Our Earth's position is "just right", not too close to our star the Sun and not too far away. Too close would result in the obvious, an overheated planet, absorbing too much radiation, unable to sustain life. Likewise if our planet was just a little further out it would not absorb enough light and radiation, turning us into our neighboring, frozen, uninhabitable planet, Mars.

Next our Sun known as a G2 star happens to be just the right size for our Earth to orbit properly around. If the Sun was smaller, so would the boundaries of the habitable zone, changing the way the Earth rotated around the Sun. The Earth would have to move closer to the Sun due to a change in its gravitational pull. Earth would likely then have one side facing the Sun while the other side of the planet remained dark and frozen. Our Sun is perfect in size to keep Earth's temperatures in a range necessary for life.

Like a good neighbor, other planets within our solar system look out for our Earth's safety. The larger planets such as Jupiter and Saturn shield Earth from possible asteroid and meteor impacts.

Earth lucked out again by having a faithful companion rotate around it. The moon is Earth's only natural satellite. 1/4 to the size of Earth, the moon remains large enough to resist Earth's gravitational pull, allowing it to aid our planet, stabilizing the Earth's axis.

The moon is also responsible for the tides, which in turn circulates the warm and cold waters of our planet, allowing for seasonal temperatures to sustain complex life.

When it comes to our planet, our Earth's uniqueness is really skin deep. Earth evolved in such a way to have a crust that is just thick enough for stability, yet moveable, with tectonic plates. Tectonic plates are composed of two types of rigid crusts, the continental and oceanic. These are floating on top of the magma interior of the Earth and can move against one another. When two plates collide, one plate can go underneath another.

This process is very important. When microscopic plants in the ocean die, they fall to the bottom of the ocean. Over long periods of time, the remnants of this life, rich in carbon, are carried back into the interior of the Earth and recycled. This pulls carbon out of the atmosphere, which makes sure we don’t get a runaway greenhouse effect, like what happened on Venus. Without the plate tectonics, there’d be no way to recycle this carbon, and the Earth would overheat.

Also, there is the magnetic field within the Earth which assists in protecting the planet from solar wind (a stream of energetic charged particles emanating from the Sun) by deflecting most of the charged particles.

Of course then there is the essential gift to life, water. About 70% of the Earth's surface is covered with water, and most of that is the ocean. Only a small portion of the Earth's water is freshwater, which is found in rivers, lakes, and groundwater. Freshwater is needed for drinking, farming, and washing. In addition to liquid water, water is also present on Earth in the form of ice. Without water, life as we know it would not exist.

78% Oxygen, 21% Nitrogen, 17% Carbon are the ingredients to our Earth's atmosphere. An atmosphere is a layer of gases that surround our planet and are kept in place by Earth's gravity. -The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.- Wikipedia

So far Earth is the only planet that we know of with this type of infused casing.

I grew up knowing our solar system, every child is introduced to it at some point in a science class. Some even had to create a replica, bent wire coat hangers with attached painted foam planets. As a child I knew Earth's location and its neighboring planets and have kept a mental image of our solar system filed away somewhere in my mind ever since. But our galaxy, that is an image to ponder. And our location within it is equally impressive.

Location, location, location any good realtor will tell you this is what you want to look for. And whether by chance or design, Earth got a prime lot. Location in our solar system, galaxy and universe can mean the difference between the lush, vibrant planet on which we live, and a barren wasteland, devoid of life.

Our solar system is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth. Almost everything that we can see in the sky belongs to the Milky Way Galaxy. And like our solar system, the Milky Way also has a habitable zone. It is located in a relatively “quiet” area nestled between two spiral arms.

Our Sun and Earth is located within a small, partial arm that is known as the Orion Arm, or Orion Spur. It is nestled safely between the spirals known as Perseus and Sagittarius. Within the center of our galaxy is a black hole. Luckily we are far enough away from it to dodge the extreme levels of X-ray and gamma radiation that emits from it.

Within the spirals of our galaxy, gases, dust and debris swirl about. Novas and supernovas explode making the spirals a volatile environment to exist within. From our position however, between the spirals, Earth maintains a clear view of the night sky, allowing us to study all that we can see, which in turn allows us to have a better understanding to our own existence.

And finally our Earth maintains a moderate rotation which allows life to exist upon it while its perfectly attuned forces (gravity-electrons-protons-nuclear-etc.) keep all its systems and balances and complex life and ecosystems in check.

There are many more complex reasons the Earth is special compared to its neighbors as well as compelling facts which lend support to the idea that maybe our planet IS the handiwork of intelligent design. But I'm no Carl Sagan, just someone who saw an interesting movie with thought provoking questions.

Somehow I can't help but think of how our planet is floating and swirling within this cosmic cluster of dust, in a sea of darkness and feel a little small. But then I think of all the gifts our planet contains which has enabled it the ability to support life, and I can't help believe that there IS a reason for it all. We must have purpose. I can't think that Earth's creation is a random act, a mere accident, pure chance.

It is true however that our galaxy is one of billions and trillions of galaxies, so certainly then you would have to think that there has to be other planets out there similar to our own. But in the meantime, we are all we know, we are all we have and as far as we know - there is only ONE planet Earth.


Check out this link to see the latest discovery of a new rocky planet made by NASA's space telescope, Kepler. http://www.youtube.com/watch?v=zjwcXd4Toms