Last time, we looked at the astronomical odds of the fine tuning necessary for life to exist on Earth, and explored six of over 35 different characteristics of fine tuning that exist in our universe. So is it just our universe that displays this precise fine tuning? Or is it also evident in our galaxy and solar system? Could natural processes accidentally have made something so uniquely tailored to support life? Or does all this precision point to a Creator?
A FINELY TUNED GALAXY
Galaxies are formations of from millions to perhaps a trillion stars. Our own galaxy is called the Milky Way. It’s unknown how many galaxies the universe contains, but it may be around a trillion. Surprisingly, given the great number of these star groups, most galaxies are incompatible with life.
In order for life to exist in a galaxy, it needs to meet several criteria.¹ The following are just three of the fine-tuned characteristics a galaxy needs to support life:
- Shape of the galaxy. The Milky Way is spiral-shaped. Of the three types of galaxies—elliptical, irregular, and spiral— the spiral type is most capable of hosting human life.
- Not too large a galaxy. Our Milky Way is enormous, measuring 100,000 light-years from end to end. However, if it were just a bit larger, too much radiation and too many gravitational disturbances would prohibit life like ours.
- Not too small a galaxy. On the other hand, a stable Earth orbit that is necessary for life could not exist if our galaxy were slightly smaller. And a smaller galaxy would result in inadequate heavy elements, such as iron and carbon, essential to life.
Our Milky Way galaxy meets these and many other conditions essential for life. Most of the others do not.
When we focus in even closer, on our own star and its planets, the odds for life being possible become even more extreme.
A FINELY TUNED SOLAR SYSTEM
Copernicus’s theory that Earth revolved around the Sun, seemed to relegate our planet to an ordinary status in the universe. However, if Earth was the center of our solar system, as Ptolemy and 16th century Catholic Church leaders had taught, we wouldn’t be here. None of them, including Copernicus, knew that in order for human life to be possible, Earth needs to revolve around a Sun that has just the right size, location, and conditions as ours does.
But that is not all. We need other planets such as Jupiter and Mars to act as defense shields, protecting us from a potential catastrophic bombardment of comets and meteors. We also need a moon of just the right size and position to impact our tides and seasons. Let’s take a look at just a few of the many conditions in our solar system that are just right for life.
- The Sun’s distance from the center of the galaxy. Our Sun is positioned thousands of light-years from the center of the Milky Way, near one of its spiral arms.² This is the safest part of the galaxy, away from its highly radioactive center.
- The Sun’s mass not too large. If the mass of the Sun were a small percentage greater, it would burn too quickly and erratically to support life.
- The Sun’s mass not too small. On the other hand, if it were smaller, its greater flaring would disrupt Earth’s rotation rate.
- The Sun’s metal content. Only two percent of all stars have enough metal content to form planets. Too much metal in a star will allow too many planets to form, creating chaos. Our Sun has just the right amount of metal for planets to form safely.
- Effect of the Moon. The Moon stabilizes the Earth’s tilt and is responsible for our seasons. If it weren’t there, our tilt could swing widely over a large range, making our winters a hundred degrees colder and our summers a hundred degrees warmer.
When astronomers consider our remarkable solar system, they acknowledge that if it was slightly different, advanced biological life would be impossible. But it is not enough to have the right universe, galaxy, and solar system for human life to be possible. The conditions of our home planet must also be fine-tuned to a razor’s edge. We’ll explore that next time.
¹ Guillermo Gonzalez and Jay W. Richards, The Privileged Planet (Washington, DC: Regnery, 2004), 132–138.
² Ibid., 132–138.