The solar system’s current position (in between two nearby exceptionally symmetrical and widely separated spiral arms that are devoid of any significant spurs or feathers) keeps the solar system’s planets well-protected from gravitational interactions with stars and dense molecular clouds. Such gravitational interactions, if present, would generate changes in the planets’ orbital parameters, including the eccentricities, inclinations, and average distances from the Sun. These changes could easily disturb the Earth’s capacity to support an abundance of advanced life.
Gravitational interactions could also alter the Sun’s orbit about the center of the Milky Way Galaxy (MWG). Currently, the Sun’s orbit departs negligibly from the plane of the MWG where radiation-absorbing dust exists in abundance. Consequently, life on Earth remains well-protected from the deadly radiation emanating from the MWG’s core. However, if the Sun were to be gravitationally perturbed, that benign circumstance could be altered.
Recently, two Mexican astronomers completed a study of the gravitational effects that would be induced upon a planetary system experiencing near encounters with other stars.1 They modeled the kinds of encounters that would be typical for various parts of the MWG and various parts of other spiral galaxies. They concluded that possibly habitable locations are much rarer than what astronomers had previously considered. The MWG is indeed exceptional in its capacity to support life. However, the real estate space within the MWG that provides a safe environment for advanced life is quite tiny.
The astronomers’ study illustrates a Christian apologetics principle. It shows that the more we learn about the physics of galaxies and planetary systems, the more evidence we accumulate for the supernatural, super-intelligent design of both the MWG and the solar system for the benefit of all life on Earth, both simple and complex.