Close Encounters of a Deadly Kind

Close Encounters of a Deadly Kind

Recent studies of the Edgeworth-Kuiper asteroid belt reveal the “amazing circumstances” required to make our solar system a suitable place for life.1 The belt itself is a recent discovery. It consists of thousands of asteroids orbiting beyond Neptune. In January 2000, an international team of astronomers recognized that the orbits of these asteroids faithfully record our sun’s close encounters with other stars over the past 4.6 billion years.

The team’s calculations show that another star approached our sun during the first hundred million years of our sun’s existence and came within ten billion miles of it. (For perspective, note that Pluto, the most distant planet, resides four billion miles out.) They also show what would have happened to our solar system if it had received additional close encounters: Many of the asteroids would have been ground into dust. This dust interacts with gas giants (such as our Jupiter) in such a way as to cause them to drift inward toward their stars. This drifting would destabilize other planets’ orbits, thus ending all possibility for life in such a system.

This drift pattern is exactly what we see in the orbits of the forty extra-solar planets discovered so far. This drift pattern, caused by close stellar encounters, is the norm for planetary systems, the team concludes. Our solar system had the extraordinary “good fortune” of forming in a very small and loose star cluster situated well away from a spiral arm where stars are more densely packed. And, because our solar system revolves around our galaxy’s core at just the right distance/rate, it remains in this safe zone, this sparsely populated area of our galaxy.2

Such “good fortune,” I would argue, combined with the many other fine-tuned characteristics that make our solar system, specifically our planet, habitable,3 can better be explained as the handiwork of God.

The research team’s calculations also show that if our solar system had received no stellar encounters, gas giants such as Uranus and Neptune would have formed beyond the orbit of Pluto. Exactly what impact these faraway gas giants would have had on the comets and asteroids in their vicinity (not to mention on the survivability of life on Earth) has yet to be determined.

  1. Shigeru Ida, John Larwood, and Andreas Burkert, “Evidence for Early Stellar Encounters in the Orbital Distribution of Edgeworth-Kuiper Belt Objects,” Astrophysical Journal, 528 (2000), pp. 1351-356.
  2. Guillermo Gonzalez and Hugh Ross, “You Must Be Here,” Facts for Faith, vol. 1, no. 1 (2000), pp. 36-41.
  3. Hugh Ross, “Design Evidences for Life Support,” (Pasadena, Calif.: Reasons To Believe, 2000).