Reasons to Believe

No Ordinary Galaxy

It is typical for many astronomers (and laypeople, too) to draw the Copernican assumption that the Milky Way Galaxy (MWG) is in no way unusual. But recently, an international team of six astronomers—including one who went to the same high school and universities as I did—has established that our galaxy had a different formation history and a different structural outcome than is the case for most other galaxies.1 Far from being ordinary, our galaxy manifests a different history and a distinct structure (see figure 1) that yields more evidence for design. 


Figure 1: Milky Way Galaxy’s Spiral Structure
This artist’s detailed rendition of the MWG shows its two dominant spiral arms, its central bar, and the extraordinary symmetry of all its spiral arms. So as to more clearly reveal the spiral structure, the 151 globular clusters that orbit about the MWG’s core have been omitted. 
Image credit: NASA/JPL-Caltech.

First, the astronomy research team reviewed how the hierarchical gravitational clustering model successfully explains the structure of the vast majority of large galaxies in the universe. As confirmed by observations of very distant galaxies (because of light-travel times, astronomers see these galaxies as they were when the universe was much younger), all large galaxies start off with disk (spiral) structures. However, galaxy collisions and merger events scramble nearly all the disk structures into collapsed spherical or elliptical configurations (see figure 2). Those spiral galaxies that survive such scrambling end up with large central bulges (see figure 3).

Figure 2: A Large Elliptical Galaxy Surrounded by Many Smaller Ellipticals
Astronomers note that about 90 percent of all present-day existing galaxies in the universe manifest either a spherical or an elliptical structure.
Image credit: NASA/ESA/Hubble Heritage Team (STScI/AURA).


Figure 3: A Typical Large Spiral Galaxy Manifesting a Large Central Bulge
The large central bulge in the Sombrero Galaxy is the result of the aftermath of earlier galaxy collisions and merger events.
Image credit: European Southern Observatory.

The research team points out, however, that the hierarchical gravitational clustering model is incomplete. It does not explain either the history or the current configuration of the MWG. Rather than the typical spherical central bulge seen in most spiral galaxies, our galaxy possesses a boxy-looking bar at its core.

The team then proceeded to develop a new model of galaxy formation that explains in considerable detail the observed properties of the MWG’s central bar (see figures 1 and 4). They showed that there is no need at all for our galaxy to have experienced, at any time in its past, any collision or merger events with other large or medium-sized galaxies. Rather, they demonstrated that the MWG’s central bar structure is actually part of the galaxy’s disk.

Beginning with plausible initial conditions for our galaxy’s disk, the team used a detailed computer simulation to show that a central bar will form and subsequently buckle vertically into the thickened state of the size and dimensions that astronomers observe. In evading collisions and/or mergers throughout its history, our galaxy sustained extremely symmetrical spiral arms, prevented the solar system from bouncing around the galaxy, and avoided the development of a large central bulge. All these conditions are requirements for a galaxy to sustain a planet potentially friendly to advanced life. 


Figure 4: Infrared Image of the Milky Way Galaxy’s Core
This deep exposure infrared image from NASA’s Spitzer Space Telescope reveals many details about the structure of the MWG’s central bar.
Image credit: NASA/JPL-Caltech.

The evidence for fine-tuning design inherent in the astronomy research team’s study is that for the MWG to maintain its advanced-life-friendly spiral structure, it must avoid collisions and mergers with large- and medium-sized galaxies while simultaneously accreting a regular supply of dwarf galaxies. If our galaxy absorbs too many dwarf galaxies in too short a time period, its structure will be distorted significantly. On the other hand, if our galaxy absorbs too few dwarf galaxies per unit of time, it will lack the infusion of gas and dust necessary to prevent the collapse of the spiral structure. All this adds up to our galaxy needing an extremely exclusive piece of real estate within the universe. We at RTB would propose that the MWG’s optimal location points to the work of an all-powerful, all-loving Creator.

Subjects: Galaxy Design

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. Read more about Dr. Hugh Ross.

Endnotes:


1. Juntai Shen et al., “Our Milky Way as a Pure-Disk Galaxy—a Challenge for Galaxy Formation,” Astrophysical Journal Letters 720 (September 1, 2010): L72–L76.