Our Privileged Planet

“We shall not cease from exploration. And the end of all our exploring will be to arrive where we started and know the place for the first time.” —T.S. Elliot

During the time of Aristotle and for 18 centuries after that, it was believed that the Sun, our solar system, and the stars rotated around the Earth in concentric circles. At the time this understanding was the basis for a very important spiritual belief—that humans were at the center of the Universe!

In 1543 Nicolaus Copernicus revealed this primordial error and proved that, in fact, the Earth was not stationary—it was only one planet circling around one of billions of stars. His discoveries were the keys that unlocked the mathematics of the Universe, and the Copernican Revolution was born. The people of the time were not excited about his discovery. Earth no longer held a preferred place in the cosmos, and as a result, neither did humanity.

Since that time, scientific discovery and spiritual perspectives have shifted back and forth, like a game of cosmic ping-pong, between the apparent insignificance of Earth and the role of Earth in the greater purpose of the Universe. On Christmas Eve 1968 the world watched as Apollo 8 rounded the dark side of the moon and laid eyes upon the awe-inspiring light of Mother Earth, our home, for the very first time. The images taken on this momentous event move me to the depths of my core.

In 1977 an historic mission was launched as two Voyagers were sent to explore our solar system. When Voyager 1 approached the edge of the solar system, it turned back toward the sun and captured unprecedented views of our home star. The Earth appeared as a small pale dot engulfed by a ray of sunlight. The image of this pinpoint of light re-inspired timeless questions about Earth’s meaning, purpose, and significance. Some saw the sunbeam that clearly pointed to our tiny planet as a sign from God that although we were, in fact, small in size we were big in importance. Carl Sagan, in his book Pale Blue Dot, expressed the sentiment of many others when he questioned the significance of the Voyager photo, stating that:

“Our planet is a lonely speck in the great enveloping cosmic dark.”

In 1923 Edwin Hubble saw for the first time the true magnitude of the Universe when what were once thought to be distant stars were found to actually be galaxies—billions of them. Apparently, not even our galaxy is unique. Scientists began to believe that habitable planets capable of sustaining complex life must be abundant in our galaxy and beyond. In the last several years, discoveries have been made that confirm this claim. Until recently, only gaseous planets had been found, much like Jupiter; however, today we have found countless planets with qualities more similar to Earth. It is no longer speculation to say that basic life exists on other planets, but the jury is still out whether there is complex or intelligent life.

Several years ago I happened upon a documentary called the Privileged Planet. The premise of the movie is that it takes many factors (about 20) to have a habitable planet. When calculating the probability of each factor existing simultaneously, the likelihood of finding planets such as our own remains exceedingly rare, even in such an expansive, abundant Universe. Some of the factors needed for a habitable planet include:

* Location in the galaxy: away from hostile supernovas, cosmic dust, and crowding
* The Goldilocks Zone: being just the right distance from the sun, not too hot, not too cold
* Protection: being surrounded by giant planets to deflect comet impacts
* Goldilocks Star: not too hot, not too cold
* Large moon: to stabilize the planet’s axis and rotate water
* Liquid water and an oxygen-rich atmosphere
* Interior heat: which produces the magnetic field that protects the planet from solar winds

This certainly seems quite miraculous, even if it isn’t unique. The movie’s most compelling argument is the coincidence that, “The same narrow circumstances that allow us to exist also provide us with the best overall setting for making scientific discoveries.”

The atmosphere of Earth is very thin and also transparent, which both allows the sunlight to reach the ground–supporting life–and also allows us a clear window through which to view the cosmos beyond our home planet. This is just one example of how the conditions that make Earth suitable for complex life are also the same conditions needed for scientific exploration of the Universe. Our location inside the galaxy is another example. We are located inside of a spiral arm about halfway between the black hole in the center, which is dangerous territory, and the outer edge, where there are not enough heavy elements to form planets. Even at this halfway point, the Earth is lucky to be located outside of the spiral arm itself, where star formations and dust would both endanger us and cloud our view. These factors for life within the galaxy also happen to be the best possible position for us to have a clear view out into the great beyond.

“The most incomprehensible thing about the Universe is that it is comprehensible.” —Einstein

Another example of this Divine design can be seen in a solar eclipse. Life on Earth is in part dependent on our beautiful moon. Without it, the Earth would not have a stable axes tilt, in which case we would not have the seasons, which would greatly reduce the capacity for diversity of life. During a solar eclipse, the sun, moon, and Earth align in a straight line. The moon moves directly between the Earth and the sun, blocking it out completely. In order for this to happen, the sun and the moon must appear as if they are the same, exact size, which they do–half of one degree. The moon is 1/400th the size of the sun, and the sun is exactly 400 times further away!

What makes eclipses amazing is not simply that they are awe-inspiring to watch, it is that because of them we have learned critical information about our sun and our planet. Only during total solar darkness, the sun’s corona, or outermost atmosphere, is visible, allowing scientists can examine the spectrum of the sun. This study has opened a portal to the physics and chemistry of the entire Universe. Eclipses are responsible for many important scientific discoveries, including helium.

During the total eclipse of May 29, 1919, Einstein’s Theory of Relativity was proven.

The Earth went from the center of the Universe to no preferred position, then from unique within the cosmos to just one of an abundance of habitable planets, and now to a world not only perfectly suited for life but destined for scientific exploration. Regardless of whether we are one or one of many, I see the wonder, the magnificence, and the purpose of life on Earth. I don’t need scientific proof for the existence of meaning and intelligent design in the Universe or to know that our home, the Earth, is a special place. Even Copernicus would be misunderstood if one said he believed his discovery made the Earth unimportant or took God out of the equation. In fact, he once stated:

“The mechanism of the Universe wrought for us by a supremely good and orderly creator… the system the best and most orderly artist of all formed for our sake.” – Nicholas Copernicus

For early scientists such as Galileo and Newton, God was not a hypothesis, it was their assumption. Today most scientists have lost their theological roots, but it is returning full circle.

In the cosmic sea of possibilities, the question remains: pale blue dot, or not?