Our Privileged Planet: How Astronomy Points to God
When I was teaching Sunday school, I did a series of classes using Lee Strobel's works. The following is from The Case for A Creator, chapter 7. While there may be the stray original item from me, I deserve no credit for what is written in this particular article. It is properly attributed to Lee Strobel in its entirety.
Carl Sagan said Earth is an average, unassuming rock spinning around an unremarkable star in a run-of-the-mill galaxy. Some scientists have estimated there are up to ten trillion advanced civilizations in the universe. Sagan believed there are one million in the Milky Way galaxy alone.
As it turns out, Earth is anything but ordinary, our sun is far from average, and even our position in the galaxy is fortuitous. Findings are suggesting that Earth is, in fact, special.
Some believe if we find water, we’ll find life, but that's not exactly right. It is true that in order to have life you need water, the universal solvent, plus carbon. But humans require 26 essential elements, bacteria about 16, intermediate life forms in between those two. Not just any planetary body will be the source of all those ingredients in the necessary forms and amounts.
Earth’s biology and geology interact very tightly with one another. So you need not only the right chemicals for life but also a planetary environment that’s tuned for life. From the magnetic field to plate tectonics to the carbon dioxide cycle, ongoing life depends on a variety of very complicated inter-actions with the planet
Additionally, one must look at safe zones. Galactic Habitable Zones are places in the galaxy where planets might be possible.
A habitable planet can't form just anywhere; there are a large number of threats to life as you go from place to place. The Big Bang produced basically just hydrogen and helium. Heavier elements were synthesized (cooked) in the interior of stars which exploded, again and again over time… We need these elements to eventually build terrestrial planets like Earth.
Not only that, but not every galaxy is conducive to life. There are three types of galaxies - spiral, elliptical and irregular.
Spiral galaxies are known as the celestial ‘pinwheel.’ Spiral galaxies optimize habitability because they provide safe zones.
We’re very far from the black hole at the center (gamma ray bursts, x-rays, particle radiation) and between spiral arms where supernovae are exploding. Our circular orbit avoids temperature extremes.
Most galaxies are elliptical. These have random orbits like bees swarming a hive, and they don’t have enough heavy elements to construct Earths.
Irregular galaxies are the worst. They are distorted and ripped apart, and supernovae are going off throughout their volume.
In terms of habitability, Earth is in the best possible place. Our location provides enough building blocks to yield an Earth, while providing a low level of threats to life. Of other planets discovered orbiting stars in recent years, most of their orbits are highly elliptical, making habitability a problem. As a matter of fact, because Jupiter’s orbit isn’t very elliptical, it doesn’t threaten to distort our round orbit.
Jupiter - more than 300 times Earth’s mass - acts as a shield to protect us from too many comet impacts. The Red Giant deflects comets and keeps many of them from coming into the inner solar system, as do Mars and Venus too.
Earth is the right distance to have liquid water. If that distance moved just 5% either way, there'd be disaster.
Our sun is just the right size - any smaller and to have liquid water a planet would need to be close enough that it would become tidally locked (always presenting the same face). Flares would be much more significant, bringing about luminosity fluctuations (temperature spikes) and particle radiation. As a yellow dwarf, our sun has a longer life span and steadily burning hydrogen, making it consistent over time. It emits the right color balance of red and blue light, necessary for efficient photosynthesis.
Our sun's composition is unique as well. It is metal rich; it has a
higher abundance of heavy elements compared to other stars of its age in this region of the galaxy. The sun’s metallicity may be near the golden mean for building Earth-size habitable terrestrial planets.
The sun is highly stable. Light output only varies by one-tenth of one percent over a full sunspot cycle (about 11 years). This prevents wild climate swings on Earth.
The sun's orbit is more nearly circular in the galaxy than most other stars of its age. This keeps us away from the galaxy's dangerous spiral arms.
The moon is also part of our cosmic conspiracy. It stabilizes the tilt of the Earth’s axis which is responsible for our seasons. Our tilt would swing wildly over a large range resulting in major temperature swings if the moon wasn’t there. The moon contributes 60% to our tides, the sun 40%. This flushes out nutrients form the continents to the oceans keeping them more nutrient rich than they would be and helps keep large-scale ocean circulation going. The ocean carries a lot of heat; this circulation keeps the temperature of the higher latitudes relatively mild.
A planet must have a minimum mass to retain an atmosphere and a minimum mass to keep heat from its interior from being lost too quickly. If earth were smaller, like Mars, it would cool down too quickly and die. If larger, with less surface relief between the ocean basins and mountains (tendency toward a smooth sphere), Earth would be a water world - and a water world is a dead world. Mountains and continents are crucial for a life-flourishing planet.
We cannot overstate the importance of plate tectonics. Of all the planets and moons in our solar system, plate tectonics are only found on Earth. The development of mountains and continents prevented a water world and drives Earth’s carbon dioxide-rock cycle balancing greenhouse gases. These cycle to Earth’s mantle and are released via volcanoes. Earth's liquid core helps generate the magnetic field which protects us from low-energy cosmic rays. The Earth's albedo also acts as another natural thermostat. Albedo is the proportion of sunlight a planet reflects via oceans, polar ice caps and even deserts, which is good for regulating the climate. Algae production acts as a natural feedback loop, uniting biology and meteorology.
And more and more scientists are concluding that perhaps one surprising purpose for which we were created is to discover and learn about our surroundings. For example, eclipses are better viewed on Earth than they would be from any other planet in our solar system. An interesting ‘coincidence’: The sun is 400 times larger than moon but also 400 times further away.
The same conditions that give us a habitable planet also make our location wonderful for scientific measurement and dis-covery. It enabled the discovery of the cosmic background radiation that helped scientists discover the Big Bang.
The moon stabilizes Earth's tilt which gives us consistent polar ice caps which make great data recorder for scientists.
The 20% oxygen in our atmosphere just happens to be perfect for metabolism of higher organisms and is the amount necessary to facilitate fire, allowing for the development of technology.
The transparency of our atmosphere allows the sciences of cosmology and astronomy to flourish.
There is no obvious reason that the very same rare properties that allow our existence would also provide the best overall setting to make discoveries about the universe.
After learning all this, perhaps it's easier to understand what led astronomer George Greenstein to raise the question: "As we survey all the evidence, the thought insistently arises that some supernatural agency - or, rather, Agency - must be involved. Is it possible that suddenly, without intending to, we have stumbled upon scientific proof of the existence of a Supreme Being? Was it God who stepped in and so providentially crafted the cosmos for our benefit?"